Muscle-Specific Nucleic Acid Regulatory Elements and Methods and Use Thereof

ABSTRACT

The present invention relates to nucleic acid regulatory elements that are able to enhance muscle-specific expression of genes, in particular expression in cardiac muscle and/or skeletal muscle, methods employing these regulatory elements and uses of these elements. Expression cassettes and vectors containing these nucleic acid regulatory elements are also disclosed. The present invention is particularly useful for applications using gene therapy, more particularly muscle-directed gene therapy, and for vaccination purposes.

FIELD

The present invention relates to nucleic acid regulatory elements thatare able to enhance muscle-specific expression of genes, methodsemploying these regulatory elements and use thereof. The inventionfurther encompasses expression cassettes, vectors and pharmaceuticalcompositions comprising these regulatory elements. The present inventionis particularly useful for applications using gene therapy, moreparticularly muscle-directed gene therapy, and for vaccination purposes.

BACKGROUND

Muscle is an attractive target for gene therapy. Gene delivery to musclecan be used to augment expression of muscle structural proteins, such asdystrophin and sarcoglycans, e.g. to treat muscular dystrophy. Inaddition, muscle can be used as a therapeutic platform to expressnon-muscle secretory/regulatory pathway proteins for diabetes,atherosclerosis, hemophilia, cancer, etc.

Efforts to deliver transgenes to muscle have focused on vectors derivedfrom adenoviruses, retroviruses, lentiviruses, and adeno-associatedviruses (AAV), and plasmids. Adenoviral vectors have a relatively largecloning capacity can be produced at high titers and display relativelyefficient transduction of muscle. Unfortunately, these vectors canelicit a robust cellular immune response against viral and sometransgene proteins. Moreover, they can evoke a rapid activation of theinnate immune system that can contribute to a dose-limiting andpotentially dangerous inflammatory immune response. Adenoviral vectorsdo not integrate into the host genome, so their ability to persist forlong periods of time is unclear. Retroviral and lentiviral vectorsintegrate stably into the target cell genome, potentially allowingpersistent gene transfer. Whereas lentiviral vectors can transduce bothdividing and non-dividing cells, conventional retroviral vectors derivedfrom Moloney murine leukemia virus (MoMLV) can only transduce dividingcells. Consequently, lentiviral vectors can be used to transducenon-dividing skeletal muscle cells, whereas these are refractory totransduction by direct injection with retroviral vectors. Nevertheless,even lentiviral transduction of skeletal muscle is not very efficient.Naked plasmid DNA displays a remarkable ability to transfer genes tomuscle. Plasmids display minimal immunogenicity and toxicity, and havean extremely large cloning capacity. The primary disadvantage ofplasmids is their relatively poor transfection efficiency under typicaldelivery protocols. Retention of plasmids is another importantconsideration.

Adeno-associated viral vector (AAV) is by far the most promising genedelivery vehicle for muscle-directed gene therapy. AAVs natural tropismto muscle cells, their long-term persistent transgene expression, theirmultiple serotypes, as well as their minimal immune response have madeAAV vectors well suited for muscle-directed gene therapy. AAV vector canbe delivered into both skeletal muscle and cardiac muscle by means oflocal, regional, and systemic administrations.

There however remain concerns regarding the efficacy and safety of somegene delivery to approaches. The major limiting factors are:insufficient and/or transient transgene expression levels, andinappropriate expression of the transgene in unwanted cell types. Inparticular, it has been shown that inadvertent transgene expression inantigen-presenting cells (APCs), increases the risk of untoward immuneresponses against the gene-modified cells and/or the therapeutictransgene product that consequently curtails long-term gene expression.

Conventional methods of vector design relied on haphazardtrial-and-error approaches whereby transcriptional enhancers werecombined with promoters to boost expression levels. Though this couldsometimes be effective, it often resulted in non-productive combinationsthat resulted in either modest or no increased expression levels of thegene of interest and/or loss of tissue specificity. Moreover, theseconventional approaches did not take into account the importance ofincluding evolutionary conserved regulatory motifs into the expressionmodules, which is particularly relevant for clinical translation.

A computational approach depending upon a modified distance differencematrix (DDM)—multidimensional scaling (MDS) strategy (De Bleser et al.2007. Genome Biol 8, R83) has proven to be useful for the in silicoidentification of clusters of evolutionary conserved transcriptionfactor binding site (TFBS) motifs associated with robust tissue-specificexpression in liver (WO 2009/130208) and heart (WO2011/051450).

There remains a need in the art for safe and efficient gene delivery tomuscle.

SUMMARY

The present inventors have relied on a modified DDM-MDS strategy (DeBleser et al., 2007) combined with an enhanced screening strategy toidentify evolutionarily conserved transcription factor binding site(TFBS) motifs associated with highly expressed muscle-specific genesdefined herein as nucleic acid regulatory elements. As shown in theexperimental section, the inventors could identify nucleic acidregulatory elements that specifically enhanced gene expression in bothheart and skeletal muscle, and skeletal muscle-specific nucleic acidregulatory elements. These regulatory elements were subsequentlyvalidated in vivo yielding efficient and tissue-specific geneexpression. This approach hence, allows for the use of lower and thussafer vector doses, while maximizing therapeutic efficacy.

The invention therefore provides the following aspects:

Aspect 1: a nucleic acid regulatory element for enhancingmuscle-specific gene expression comprising, consisting essentially of,or consisting of a functional fragment of a to sequence selected fromthe group consisting of: SEQ ID NO:1, SEQ ID NO:2, SEQ ID NO:3, SEQ IDNO:4, SEQ ID NO:5, SEQ ID NO:6, SEQ ID NO:7, SEQ ID NO:8, SEQ ID NO:9,SEQ ID NO:10, SEQ ID NO:11, SEQ ID NO:12, SEQ ID NO:13, a sequencehaving at least 80%, preferably at least 85%, more preferably at least90%, even more preferably at least 95%, such as 95%, 96%, 97%, 98%, or99%, identity to any of these sequences, wherein said functionalfragment comprises at least 20, preferably at least 25, more preferablyat least 50, at least 100, at least 200 or at least 250, contiguousnucleotides from the sequence from which it is derived, and wherein saidfunctional fragment comprises at least 1, preferably at least 5, morepreferably at least 10 or at least 15, of the transcription factorbinding sites (TFBS) that are present in the sequence from which it isderived.

Aspect 2: the nucleic acid regulatory element according to aspect 1 forenhancing cardiac and skeletal muscle-specific gene expression,comprising a functional fragment of a sequence selected from the groupconsisting of: SEQ ID NO:1, SEQ ID NO:2, SEQ ID NO:3, SEQ ID NO:4, SEQID NO:5, SEQ ID NO:6, or a sequence having at least 80%, preferably atleast 85%, more preferably at least 90%, even more preferably at least95%, such as 95%, 96%, 97%, 98%, or 99%, identity to any of thesesequences, wherein said functional fragment comprise at least 20,preferably at least 25, more preferably at least 50, at least 100, atleast 200 or at least 250, contiguous nucleotides from the sequence fromwhich it is derived, and wherein said functional fragment comprises atleast 1, preferably at least 5, more preferably at least 10 or at least15, of the transcription factor binding sites (TFBS) that are present inthe sequence from which it is derived.

Aspect 3: the nucleic acid regulatory element according to aspect 1 forenhancing skeletal muscle-specific gene expression comprising afunctional fragment of a sequence selected from the group consisting of:SEQ ID NO:7, SEQ ID NO:8, SEQ ID NO:9, SEQ ID NO:10, SEQ ID NO:11, SEQID NO:12, SEQ ID NO:13, a sequence having at least 80%, preferably atleast 85%, more preferably at least 90%, even more preferably at least95%, such as 95%, 96%, 97%, 98%, or 99%, identity to any of thesesequences, wherein said functional fragment comprise at least 20,preferably at least 25, more preferably at least 50, at least 100, atleast 200 or at least 250, contiguous nucleotides from the sequence fromwhich it is derived, and wherein said functional fragment comprises atleast 1, preferably at least 5, more preferably at least 10 or at least15, of the transcription factor binding sites (TFBS) that are present inthe sequence from which it is derived.

Aspect 4: the nucleic acid regulatory element according to aspect 1, 2,or 3, comprising, consisting essentially of, or consisting of a sequenceselected from the group consisting of: the nucleotide sequence fromposition 33 to 58 in SEQ ID NO:1; the nucleotide sequence from position90 to 142 in SEQ ID NO:1; the nucleotide sequence from position 143 to233 in SEQ ID NO:1; the nucleotide sequence from position 240 to 310 inSEQ ID NO:1; the nucleotide sequence from position 90 to 233 in SEQ IDNO:1; the nucleotide sequence from position 47 to 130 in SEQ ID NO:5;the nucleotide sequence from position 252 to 293 in SEQ ID NO:5; thenucleotide sequence from position 330 to 450 in SEQ ID NO:5; thenucleotide sequence from position 10 to 180 in SEQ ID NO:10 (i.e. SEQ IDNO:37); the nucleotide sequence from position 190 to 240 in SEQ ID NO:10(i.e. SEQ ID NO:38); the nucleotide sequence from position 241 to 300 inSEQ ID NO:10 (i.e. SEQ ID NO:39); the nucleotide sequence from position241 to 360 in SEQ ID NO:10 (i.e. SEQ ID NO:41); the nucleotide sequencefrom position 380 to 420 in SEQ ID NO:10 (i.e. SEQ ID NO:40); or asequence having at least 95% identity to any of said sequences.

Aspect 5: the nucleic acid regulatory element according to any one ofaspects 1 to 4 comprising, consisting essentially of or consisting of asequence selected from the group consisting of: the nucleotide sequencefrom position 33 to 310 in SEQ ID NO:1; the nucleotide sequence fromposition 47 to 450 in SEQ ID NO:5; the nucleotide sequence from position10 to 420 in SEQ ID NO:10, or a sequence having at least 95% identity toany of said sequences.

Aspect 6: the nucleic acid regulatory element according to any one ofaspects 1 to 5, comprising, consisting essentially of, or consisting ofa sequence selected from the group consisting of: SEQ ID NO:1, SEQ IDNO:2, SEQ ID NO:3, SEQ ID NO:4, SEQ ID NO:5, SEQ ID NO:6, SEQ ID NO:7,SEQ ID NO:8, SEQ ID NO:9, SEQ ID NO:10, SEQ ID NO:11, SEQ ID NO:12, SEQID NO:13, or a sequence having at least 80%, preferably at least 85%,more preferably at least 90%, even more preferably at least 95%, such as95%, 96%, 97%, 98%, or 99%, identity to any of these sequences.

Aspect 7: the nucleic acid regulatory element according to any one ofaspects 1, 2, or 4 to 6 for enhancing cardiac and skeletalmuscle-specific gene expression comprising, consisting essentially of,or consisting of a sequence selected from the group consisting of: SEQID NO:1, SEQ ID NO:2, SEQ ID NO:3, SEQ ID NO:4, SEQ ID NO:5, SEQ IDNO:6, or a sequence having at least 80%, preferably at least 85%, morepreferably at least 90%, even more preferably at least 95%, such as 95%,96%, 97%, 98%, or 99%, identity to any of these sequences.

Aspect 8: the nucleic acid regulatory element according to any one ofaspects 1, 3 to 6 for enhancing skeletal muscle-specific gene expressioncomprising, consisting essentially of, or consisting of a sequenceselected from the group consisting of: SEQ ID NO:7, SEQ ID NO:8, SEQ IDNO:9, SEQ ID NO:10, SEQ ID NO:11, SEQ ID NO:12, SEQ ID NO:13, or asequence having at least 80%, preferably at least 85%, more preferablyat least 90%, even more preferably at least 95%, such as 95%, 96%, 97%,98%, or 99%, identity to any of these sequences.

Aspect 9: the nucleic acid regulatory element according to any one ofaspects 1 to 8, comprising, consisting essentially of, or consisting ofa sequence selected from the group consisting of: SEQ ID NO:17, SEQ IDNO:18, SEQ ID NO:19, SEQ ID NO:20, SEQ ID NO:21, SEQ ID NO:22, SEQ IDNO:23, SEQ ID NO:24, SEQ ID NO:25, SEQ ID NO:26, SEQ ID NO:27, SEQ IDNO:28, SEQ ID NO:29, a functional fragment thereof comprising SEQ IDNO:1, SEQ ID NO:2, SEQ ID NO:3, SEQ ID NO:4, SEQ ID NO:5, SEQ ID NO:6,SEQ ID NO:7, SEQ ID NO:8, SEQ ID NO:9, SEQ ID NO:10, SEQ ID NO:11, SEQID NO:12, or SEQ ID NO:13, or a sequence having at least 80%, preferablyat least 85%, more preferably at least 90%, even more preferably atleast 95%, such as 95%, 96%, 97%, 98%, or 99%, identity to any of thesesequences.

Aspect 10: the nucleic acid regulatory element according to any one ofaspects 1, 2, 4 to 7, 9, comprising, consisting essentially of, orconsisting of a sequence selected from the group consisting of: SEQ IDNO:17, SEQ ID NO:18, SEQ ID NO:19, SEQ ID NO:20, SEQ ID NO:21, SEQ IDNO:22, a functional fragment thereof comprising SEQ ID NO:1, SEQ IDNO:2, SEQ ID NO:3, SEQ ID NO:4, SEQ ID NO:5, or SEQ ID NO:6, or asequence having at least 80%, preferably at least 85%, more preferablyat least 90%, even more preferably at least 95%, such as 95%, 96%, 97%,98%, or 99%, identity to any of these sequences.

Aspect 11: the nucleic acid regulatory element according to any one ofaspects 1, 3 to 6, 8, or 9, comprising, consisting essentially of, orconsisting of a sequence selected from the group consisting of: SEQ IDNO:23, SEQ ID NO:24, SEQ ID NO:25, SEQ ID NO:26, SEQ ID NO:27, SEQ IDNO:28, SEQ ID NO:29, a functional fragment thereof comprising SEQ IDNO:7, SEQ ID NO:8, SEQ ID NO:9, SEQ ID NO:10, SEQ ID NO:11, SEQ IDNO:12, or SEQ ID NO:13, or a sequence having at least 80%, preferably atleast 85%, more preferably at least 90%, even more preferably at least95%, such as 95%, 96%, 97%, 98%, or 99%, identity to any of thesesequences.

Aspect 12: a nucleic acid regulatory element for enhancingmuscle-specific gene expression comprising, consisting essentially of,or consisting of the complement of a sequence as defined in any one ofaspects 1 to 11.

Aspect 13: a nucleic acid regulatory element for enhancingmuscle-specific gene expression hybridizing under stringent conditionsto the nucleic acid regulatory element according to any one of aspects 1to 12.

Aspect 14: the nucleic acid regulatory element according to any one ofaspects 1 to 13, having a maximal length of 1000 nucleotides, preferably800 nucleotides, more preferably 600 nucleotides, such as 550nucleotides, 500 nucleotides, 450 nucleotides, 400 nucleotides, 350nucleotides, or 300 nucleotides, still comprising the regulatory elementdefined by any one of SEQ ID Nos: 1-13, or any one of the functionalfragments thereof defined in any one of aspects 3 to 5.

Aspect 15: use of the nucleic acid regulatory element according to anyone aspects 1 to 14 in a nucleic acid expression cassette, or a vector,more particularly for enhancing muscle-specific expression of saidnucleic acid expression cassette or vector.

Aspect 16: a nucleic acid expression cassette comprising at least one,such as one, two, three, four, five or more, nucleic acid regulatoryelement according to any one of aspects 1 to 14, operably linked to apromoter.

Aspect 17: the nucleic acid expression cassette according to aspect 16,wherein the nucleic acid regulatory element is operably linked to apromoter and a transgene.

Aspect 18: the nucleic acid expression cassette according any one ofaspects 16 or 17, wherein the promoter is a muscle-specific promoter,preferably the promoter from the desmin (DES) gene.

Aspect 19: the nucleic acid expression cassette according to any one ofaspects 17 or 18, wherein the transgene encodes a therapeutic protein oran immunogenic protein.

Aspect 20: the nucleic acid expression cassette according to any one ofaspects 17 to 19, wherein the transgene encodes a secretable protein ora structural protein, such as dystrophin or sarcoglycan.

Aspect 21: the nucleic acid expression cassette according to any one ofaspects 16 to 20, further comprising an intron, preferably the MinuteVirus of Mouse (MVM) intron.

Aspect 22: the nucleic acid expression cassette according to any one ofaspects 16 to 21, further comprising a polyadenylation signal,preferably the Simian Virus 40 (SV40) polyadenylation signal.

Aspect 23: a vector comprising the nucleic acid regulatory elementaccording to any one of aspects 1 to 14, or the nucleic acid expressioncassette according to any one of aspects 16 to 22.

Aspect 24: the vector according to aspect 23, which is a viral vector,preferably an adeno-associated viral (AAV) vector, more preferably anAAV9 vector.

Aspect 25: the vector according to aspect 23, which is a non-viralvector, preferably a plasmid, a minicircle or a transposon-based vector,such as a PiggyBac-based vector or a Sleeping Beauty-based vector.

Aspect 26: a pharmaceutical composition comprising the nucleic acidexpression cassette according to any one of aspects 16 to 22, or thevector according to any one of aspects 23 to 25, and a pharmaceuticallyacceptable carrier.

Aspect 27: the nucleic acid regulatory element according to any one ofaspects 1 to 14, the nucleic acid expression cassette according to anyone of aspects 16 to 22, the vector according to any one of aspects 23to 25, or the pharmaceutical composition according to aspect 26 for usein medicine.

Aspect 28: the nucleic acid regulatory element according to any one ofaspects 1 to 14, the nucleic acid expression cassette according to anyone of aspects 16 to 22, the vector according to any one of aspects 23to 25, or the pharmaceutical composition according to aspect 26 for usein gene therapy, preferably muscle-directed gene therapy.

Aspect 29: the nucleic acid regulatory element, the nucleic acidexpression cassette, the vector, or the pharmaceutical compositionaccording for use according to aspect 28, wherein the gene therapy isfor muscular dystrophy (e.g. Duchenne muscular dystrophy (DMD)/Beckermuscular dystrophy (BMD)), myotonic dystrophy, neuromuscular disease,motor neuron diseases (MND), such as e.g. Charcot-Marie-Tooth disease(CMT), spinal muscular atrophy (SMA), and amyotrophic lateral sclerosis(ALS), Emery-Dreifuss muscular dystrophy, facioscapulohumeral musculardystrophy (FSHD), congenital muscular dystrophies, congenitalmyopathies, limb girdle muscular dystrophy, metabolic myopathies, muscleinflammatory diseases, myasthenia, mitochondrial myopathies, anomaliesof ionic channels, nuclear envelop diseases, cardiomyopathies, cardiachypertrophy, heart failure, distal myopathies, cardiovascular diseases,hemophilia, including hemophilia A and B, and diabetes.

Aspect 30: the nucleic acid regulatory element according to any one ofaspects 1 to 14, the nucleic acid expression cassette according to anyone of aspects 16 to 22, the vector according to any one of aspects 23to 25, or the pharmaceutical composition according to aspect 26 for useas a vaccine, preferably a prophylactic vaccine, or for use invaccination therapy, preferably prophylactic vaccination.

Aspect 31: A method, preferably an in vitro or ex vivo method, forexpressing a transgene to product in muscle cells, preferably heartmuscle cells and/or skeletal muscle cells, comprising:

-   -   introducing the nucleic acid expression cassette according to        any one of aspects 16 to 22, or the vector according to any one        of aspects 23 to 25 into the muscle cells;    -   expressing the transgene product in the muscle cells.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1: Flow diagram of the identification and validation of nucleicacid regulatory elements. A computational approach was used to identifythe nucleic acid regulatory elements involving the following steps: (1)identification of tissue-specific genes that are highly expressed e.g.based on statistical analysis of micro-array expression data of normalhuman tissues; (2) extraction of the corresponding promoter sequencesfrom publicly available databases; (3) identification of the regulatorymodules and the transcription factor binding sites (TFBS) they contain(4) Next, the genomic context of the highly expressed genes was searchedfor evolutionary conserved clusters of TFBS (i.e. nucleic acidregulatory elements). The identified nucleic acid regulatory elementswere de novo designed and validated in vivo by testing whether inclusionin a construct increases expression of a reporter gene.

FIGS. 2A-2F: Nucleotide sequences of the cardiac and skeletalmuscle-specific regulatory elements CSk-SH1 (FIG. 2A, SEQ ID NO: 1),CSk-5H2 (FIG. 2B, SEQ ID NO: 2), CSk-5H3 (FIG. 2C, SEQ ID NO: 3),CSk-5H4 (FIG. 2D, SEQ ID NO: 4), CSk-5H5 (FIG. 2E, SEQ ID NO: 5), andCSk-5H6 (FIG. 2F, SEQ ID NO: 6).

FIG. 3 shows a schematic representation of theAAV9sc-CSk-SH/Sk-SH-Des-Luc2 vectors disclosed herein. The expressioncassette was packaged in a self-complementary (sc) adeno-associatedvirus, serotype 9 (AAV9). The cardiac and skeletal muscle-specificdesmin (Des) promoter regulates transcription of the luciferase (Luc2)transgene. The identified cardiac and skeletal muscle-specific (CSk-SH)or muscle-specific (Sk-SH) nucleic acid regulatory elements were clonedupstream of the Des promoter. The expression cassette further comprisesthe Minute Virus of Mouse (MVM) intron and a Simian virus 40 (SV40)polyadenylation signal (pA). The expression cassette is flanked byinverted terminal repeats (ITR) from adeno-associated virus, serotype 2(AAV2).

FIGS. 4A-4B: Difference in luciferase expression (FIG. 4A) and Luc mRNAlevel (FIG. 4B) in heart and muscle tissue of mice that wereintravenously injected with, from left to right, AAV9sc-CSk-SH1-Des-Luc2(CSk-SH1), AAV9sc-CSk-SH2-Des-Luc2 (CSk-SH2), to AAV9sc-CSk-SH3-Des-Luc2(CSk-SH3), AAV9sc-CSk-SH4-Des-Luc2 (CSk-SH4), AAV9sc-CSk-SH5-Des-Luc2(CSk-SH5), or AAV9sc-CSk-SH6-Des-Luc2 (CSk-SH6) vector compared to micethat were injected with the control vector AAV9sc-Des-Luc2 withoutnucleic acid regulatory element (control, no Csk-SH). Luciferaseexpression was measured as total flux, expressed in photons per secondper centimetre squared per steradian (photons/sec/cm²/sr), released byluciferase activity in the selected tissues at 9 weeks post-injection.Results were presented as mean±standard error of the mean, *p<0.05;**p<0.001. Luc mRNA levels were measured by a quantitative RT-PCR method(qRT-PCR) at the end of the experiment from total RNA extracted frombiopsies from the indicated tissues. Results were presented asmean±standard error of the mean, *p<0.05; **p<0.001.

FIG. 5A Luciferase expression in selected tissues of mice that wereintravenously injected with, from left to right, AAV9sc-Des-Luc2(control, no CSk-SH), AAV9sc-CSk-SH1-Des-Luc2 (CSk-SH1),AAV9sc-CSk-SH2-Des-Luc2 (CSk-SH2), AAV9sc-CSk-SH3-Des-Luc2 (CSk-SH3),AAV9sc-CSk-SH4-Des-Luc2 (CSk-SH4), AAV9sc-CSk-SH5-Des-Luc2 (CSk-SH5), orAAV9sc-CSk-SH6-Des-Luc2 (CSk-SH6) vector. Luciferase expression wasmeasured as total flux, expressed in photons per second per centimetresquared per steradian (photons/sec/cm²/sr), released by luciferaseactivity in the selected tissue at 9 weeks post-injection. Results werepresented as mean±standard error of the mean. FIG. 5B Luc mRNA level inselected tissues of mice that were intravenously injected with, fromleft to right, AAV9sc-CSk-SH1-Des-Luc2 (CSk-SH1),AAV9sc-CSk-SH2-Des-Luc2 (CSk-SH2), AAV9sc-CSk-SH3-Des-Luc2 (CSk-SH3),AAV9sc-CSk-SH4-Des-Luc2 (CSk-SH4), AAV9sc-CSk-SH5-Des-Luc2 (CSk-SH5), orAAV9sc-CSk-SH6-Des-Luc2 (CSk-SH6) vector compared to mice that wereinjected with the control vector AAV9sc-Des-Luc2 (control, no Csk-SH).Luc mRNA levels were measured by a quantitative RT-PCR method (qRT-PCR)at the end of the experiment from total RNA extracted from biopsies fromthe indicated tissues. Results were presented as mean±standard error ofthe mean.

FIG. 6: Transduction efficiency in different organs of mice injectedwith AAV9sc-CSk-SH1-Des-Luc2 (CSk-SH1) (A) or AAV9sc-CSk-SH5-Des-Luc2(CSk-SH5) (B). AAV copy number relative to 100 ng of genomic DNA wasdetermined for both constructs at a dose of 5×10⁹ vg/mouse.

FIGS. 7A-7G: Nucleotide sequences of the muscle-specific regulatoryelements Sk-SH1 (FIG. 7A, SEQ ID NO: 7), Sk-SH2 (FIG. 7B, SEQ ID NO: 8),Sk-SH3 (FIG. 7C, SEQ ID NO: 9), Sk-SH4 (FIG. 7D, SEQ ID NO: 10), Sk-SH5(FIG. 7E, SEQ ID NO: 11), Sk-SH6 (FIG. 7F, SEQ ID NO: 12), Sk-SH7 (FIG.7G, SEQ ID NO: 13).

FIG. 8 shows difference in luciferase expression in heart and muscletissue of mice that were intravenously injected with, from left toright, AAV9sc-Sk-SH1-Des-Luc2 (Sk-SH1, n=4), AAV9sc-Sk-SH2-Des-Luc2(Sk-SH2, n=4), AAV9sc-Sk-SH3-Des-Luc2 (Sk-SH3, n=4),AAV9sc-Sk-SH4-Des-Luc2 (Sk-SH4, n=4), AAV9sc-Sk-SH5-Des-Luc2 (Sk-SH5,n=1), AAV9sc-Sk-SH6-Des-Luc2 (Sk-SH5, n=3) or AAV9sc-Sk-SH7-Des-Luc2(Sk-SH6, n=4) vector compared to mice that were injected with thecontrol vector AAV9sc-Des-Luc2 without nucleic acid regulatory element(control, no Sk-SH, n=5). Luciferase expression was measured as totalflux, expressed in photons per second per centimetre squared persteradian (photons/sec/cm²/sr), released by luciferase activity in theselected tissues at 7 weeks post-injection. Results were presented asmean±standard error of the mean, *p<0.05; **p<0.001.

FIG. 9 shows luciferase expression in selected tissues of mice that wereintravenously injected with, from left to right, AAV9sc-Des-Luc2(control, no Sk-SH, n=5), AAV9sc-Sk-SH1-Des-Luc2 (Sk-SH1, n=4),AAV9sc-Sk-SH2-Des-Luc2 (Sk-SH2, n=4), AAV9sc-Sk-SH3-Des-Luc2 (Sk-SH3,n=4), AAV9sc-Sk-SH4-Des-Luc2 (Sk-SH4, n=4), AAV9sc-Sk-SH5-Des-Luc2(Sk-SH5, n=1), AAV9sc-Sk-SH6-Des-Luc2 (Sk-SH5, n=3), orAAV9sc-Sk-SH7-Des-Luc2 (Sk-SH6, n=4) vector. Luciferase expression wasmeasured as total flux, expressed in photons per second per centimetresquared per steradian (photons/sec/cm²/sr), released by luciferaseactivity in the selected tissue at 7 weeks post-injection. Results werepresented as mean±standard error of the mean, *p<0.05; **p<0.001.

FIG. 10A Schematic diagram of the AAVsc-CMV-Luc2-SV40 pA plasmidconstruct with indication where the Cytomegalovirus promoter (CMVp) iscloned upstream of the Firefly Luciferase gene (Luc2). Abbreviationsused are: ITR: viral inverted terminal repeat; SV40 pA: Simian Virus 40polyadenylation site. FIG. 10B Luciferase expression in selected tissuesof mice that were intravenously injected with, from left to right,AAV9sc-CMV-Luc2 (CMV, n=4), AAV9sc-Sk-SH4-Des-Luc2 (Sk-SH4, n=2),AAV9sc-CSk-SH1-Des-Luc2 (CSk-SH1, n=4), or AAV9sc-CSk-SH5-Des-Luc2(CSk-SH5, n=4) vector. Luciferase expression was measured as total flux,expressed in photons per second per centimetre squared per steradian(photons/sec/cm²/sr), released by luciferase activity in the selectedtissue. Results were presented as mean±standard error of the mean. FIG.10C Difference in luciferase expression in heart and muscle tissue ofmice that were intravenously injected with, from left to right,AAV9sc-Sk-SH4-Des-Luc2 (Sk-SH4, n=2), AAV9sc-CSk-SH1-Des-Luc2 (CSk-SH1,n=4), or AAV9sc-CSk-SH5-Des-Luc2 (CSk-SH5, n=4) vector compared to micethat were injected with vector AAV9sc-CMV-Luc2 (CMV, n=4). Luciferaseexpression was measured as total flux, expressed in photons per secondper centimetre squared per steradian (photons/sec/cm²/sr), released byluciferase activity in the selected tissues at 7 weeks post-injection.Results were presented as mean±standard error of the mean.

FIGS. 11A-11C shows functional fragments and the indicated transcriptionbinding sites (TFBS) of CSk-SH1 (FIG. 11A), CSk-SH-5 (FIG. 11B), andSk-SH4 (FIG. 11C) mapped on a schematic representation of respectively,SEQ ID NO:1 (FIG. 11A), SEQ ID NO:5 (FIG. 11B), and SEQ ID NO:10 (FIG.11C).

FIG. 12: Difference in Luc mRNA level in heart and muscle tissue of micethat were intravenously injected with, from left to right,AAV9sc-Sk-SH1-Des-Luc2 (Sk-SH1), AAV9sc-Sk-5H2-Des-Luc2 (Sk-5H2),AAV9sc-Sk-5H3-Des-Luc2 (Sk-5H3), AAV9sc-Sk-SH4-Des-Luc2 (Sk-SH4),AAV9sc-Sk-5H6-Des-Luc2 (Sk-5H6), or AAV9sc-Sk-SH7-Des-Luc2 (Sk-SH7)vector compared to mice that were injected with the control vectorAAV9sc-Des-Luc2 without nucleic acid regulatory element (control, noSk-SH). Luc mRNA levels were measured by a quantitative RT-PCR method(qRT-PCR) from total RNA extracted from biopsies from the indicatedtissues. Results were presented as mean±standard error of the mean,*p<0.05; **p<0.001.

FIG. 13: Transduction efficiency in different organs of mice injectedwith AAV9sc-Sk-SH4-Des-MVM-Luc-pA vector (A) orAAV9sc-Sk-SH1-Des-MVM-Luc-pA vector (B). AAV copy number relative to 100ng of genomic DNA was determined for both vectors (n=3).

FIG. 14 shows luciferase expression in heart and muscle tissue of micethat were intravenously injected with, from left to right,AAV9sc-Des-Luc (control, no Sk-SH), AAV9sc-Sk-SH4-Des-Luc (Sk-SH4),AAV9sc-Sk-SH4^(a)d-Des-Luc (Sk-SH4^(a)), AAV9sc-Sk-SH4^(b)-Des-Luc(Sk-SH4^(b)), AAV9sc-Sk-SH4^(c)-Des-Luc (Sk-SH4^(d)),AAV9sc-Sk-SH4^(d)-Des-Luc (Sk-SH4^(e)), or AAV9sc-Sk-SH4^(e)-Des-Luc(Sk-SH4^(e)) vector. Luciferase expression was measured as total flux,expressed in photons per second per centimetre squared per steradian(photons/sec/cm²/sr), released by luciferase activity in the selectedtissue 5 weeks post-injection. Results were presented as mean±standarderror of the mean. The fold difference in luciferase expression in miceinjected with Sk-SH4 and Sk-SH4^(b) compared to mice that were injectedwith the control vector AAV9sc-Des-Luc2 without nucleic acid regulatoryelement is indicated.

FIGS. 15A-150: Chromatin immunoprecipitation (CHIP) assay for heart(FIG. 15A, FIG. 15C) and muscle (FIG. 15B, FIG. 15D) tissue of miceinjected with AAV9sc-Sk-SH4-Des-Luc (FIG. 15A, FIG. 15B) orAAV9sc-CSk-SH5-Des-Luc (FIG. 15C, FIG. 15D) (5×10⁹ vg/mouse). Antibodiesspecific for the transcription factors CEBP, SRF and MEF2 were used. PCRprimers were designed to amplify a region of Sk-SH4 that binds CEBP andSRF, or a region of CSk-SH5 that bind CEBP and MEF2, and as negativecontrol (−) an un-transcribed region on chromosome 17 was used. Bindingevents for 10³ cells were determined for each of the correspondingprimer pairs. Results are presented as mean±standard error of the mean.Significant difference compared to the negative control is indicated(t-test, *P≤0.05).

FIGS. 16A-16D shows schematic representations of single-stranded (ss)AAV plasmid constructs disclosed herein, which comprise themicrodystrophin1 (MD1) (FIG. 16A, AAVss-SkSH4-Des-MVM-MD1) orfollistatin (FST) (FIG. 16C, AAVssSkSH4-Des-MVM-FST-2A-Luc2) transgeneregulated by the Desmin promoter operably linked to the muscle-specificnucleic acid regulatory element SkSH4 cloned upstream of the Desminpromoter. The follistatin gene was linked to the Luc2 reporter gene viaa 2A peptide. The expression cassettes further comprise the Minute Virusof Mouse (MVM) intron and the 49 bp synthetic Proudfoot polyadenylationsite (pA). The expression cassettes are flanked by inverted terminalrepeats (ITR). FIG. 16B Nucleotide sequence of theAAVss-SkSH4-Des-MVM-MD1 plasmid construct (SEQ ID NO:44). FIG. 16DNucleotide sequence of the AAVss-SkSH4-Des-MVM-FST-2A-Luc2 plasmidconstruct (SEQ ID NO:45).

FIG. 17: Treadmill test for MDX-SCID mice injected with, from left toright, PBS (control), AAVss-Sk-SH4-Des-MVM-FST-2A-Luc,AAVss-Sk-SH4-Des-MVM-MD1, or the combination ofAAVss-Sk-SH4-Des-MVM-FST-2A-Luc and AAVss-Sk-SH4-Des-MVM-MD1. Resultsare expressed as the calculated distance covered by each group of micewhen run on a treadmill machine.

FIG. 18: (A) Hematoxylin/eosin staining of gastrocnemius muscle tissuesof MDX/SCID mice injected with PBS (a, control),AAVss-Sk-SH4-Des-MVM-FST-2A-Luc (b), AAVss-Sk-SH4-Des-MVM-MD1 (c) or thecombination of AAVss-Sk-SH4-Des-MVM-MD1 andAAVss-Sk-SH4-Des-MVM-FST-2A-Luc (d). (B) Quantification of centrallynucleated cells in wild-type C57Bl/6 mice, untreated MDX/SCID mice(control), and MDX/SCID mice injected with AAVss-Sk-SH4-Des-MVM-MD1(MD1), AAVss-Sk-SH4-Des-MVM-FST-2A-Luc (FST) or both (FST+MD1)therapeutic vectors. Statistical analysis was performed on H&E-stainedtransversally transected myofibers of gastronemius muscle embedded inparaffin. ***≤0.0001 **≤0.001 *≤0.05

FIGS. 19A-19C: Microdystrophin1 (MD1) (FIG. 19A, FIG. 19B) andfollistatin (FST) (FIG. 19C) mRNA levels in heart and muscle(gastrocnemius and quadriceps) tissues from mice that were intravenouslyinjected with the AAVss-Sk-SH4-Des-MVM-MD1 vector (FIG. 19A), thecombination of AAVss-Sk-SH4-Des-MVM-MD1 andAAVss-Sk-SH4-Des-MVM-FST-2A-Luc (FIG. 19B), or AAVss-Sk-SH4-Des-MVM-FST(FIG. 19C) relative to expression of endogenous housekeeping gene(GAPDH: Glyceraldehyde-3-phosphate dehydrogenase). Results are presentedas relative expression of MD1 or FST (ΔΔCT).

FIG. 20 shows schematic representations of self-complementary (sc) AAVconstructs disclosed herein, which comprise the luciferase (Luc)transgene regulated by (a) the cardiac and skeletal muscle-specificdesmin (Desmin) promoter, (b) the SPc5-12 promoter, (c) thecytomegalovirus (CMV) promoter, (d) the Desmin promoter operably linkedto a muscle-specific (Sk-SH) nucleic acid regulatory element clonedupstream of the Desmin promoter, or (e) the SPc5-12 promoter operablylinked to a muscle-specific (Sk-SH) nucleic acid regulatory elementcloned upstream of the SPc5-12 promoter. Expression cassettes (a), (b),(d) and (e) further comprise the Minute Virus of Mouse (MVM) intron anda polyadenylation signal (pA). The expression cassettes are flanked byinverted terminal repeats (ITR).

FIG. 21: Difference in Luc mRNA levels in selected tissues ofCB17/IcrTac/Prkdcscid mice that were intravenously injected with, fromleft to right, AAVsc-CMV-Luc, AAVsc-Des-MVM-Luc,AAVsc-Sk-SH4-Des-MVM-Luc, AAVsc-SPc5-12-MVM-Luc orAAVsc-Sk-SH4-SPc5-12-MVM-Luc vector as schematically shown in FIG. 20,compared to mice that were injected with AAVsc-CMV-Luc vector. Luc mRNAlevels were measured by qRT-PCR from total RNA extracted from biopsiesof the indicated tissues. Results were presented as mean±standard errorof the mean, *p<0.05; **p<0.001.

DESCRIPTION

As used herein, the singular forms “a”, “an”, and “the” include bothsingular and plural referents unless the context clearly dictatesotherwise.

The terms “comprising”, “comprises” and “comprised of” as used hereinare synonymous with “including”, “includes” or “containing”, “contains”,and are inclusive or open-ended and do not exclude additional,non-recited members, elements or method steps. The terms also encompass“consisting of” and “consisting essentially of”, which enjoywell-established meanings in patent terminology.

The recitation of numerical ranges by endpoints includes all numbers andfractions subsumed within the respective ranges, as well as the recitedendpoints.

The terms “about” or “approximately” as used herein when referring to ameasurable value such as a parameter, an amount, a temporal duration,and the like, are meant to to encompass variations of and from thespecified value, such as variations of +/−10% or less, preferably +/−5%or less, more preferably +/−1% or less, and still more preferably+/−0.1% or less of and from the specified value, insofar such variationsare appropriate to perform in the disclosed invention. It is to beunderstood that the value to which the modifier “about” refers is itselfalso specifically, and preferably, disclosed.

Whereas the terms “one or more” or “at least one”, such as one or moremembers or at least one member of a group of members, is clear per se,by means of further exemplification, the term encompasses inter alia areference to any one of said members, or to any two or more of saidmembers, such as, e.g., any or etc. of said members, and up to all saidmembers. In another example, “one or more” or “at least one” may referto 1, 2, 3, 4, 5, 6, 7 or more.

The discussion of the background to the invention herein is included toexplain the context of the invention. This is not to be taken as anadmission that any of the material referred to was published, known, orpart of the common general knowledge in any country as of the prioritydate of any of the claims.

Throughout this disclosure, various publications, patents and publishedpatent specifications are referenced by an identifying citation. Alldocuments cited in the present specification are hereby incorporated byreference in their entirety. In particular, the teachings or sections ofsuch documents herein specifically referred to are incorporated byreference.

Unless otherwise defined, all terms used in disclosing the invention,including technical and scientific terms, have the meaning as commonlyunderstood by one of ordinary skill in the art to which this inventionbelongs. By means of further guidance, term definitions are included tobetter appreciate the teaching of the invention. When specific terms aredefined in connection with a particular aspect of the invention or aparticular embodiment of the invention, such connotation is meant toapply throughout this specification, i.e., also in the context of otheraspects or embodiments of the invention, unless otherwise defined.

In the following passages, different aspects or embodiments of theinvention are defined in more detail. Each aspect or embodiment sodefined may be combined with any other aspect(s) or embodiment(s) unlessclearly indicated to the contrary. In particular, any feature indicatedas being preferred or advantageous may be combined with any otherfeature or features indicated as being preferred or advantageous.

Reference throughout this specification to “one embodiment”, “anembodiment” means that a particular feature, structure or characteristicdescribed in connection with the to embodiment is included in at leastone embodiment of the present invention. Thus, appearances of thephrases “in one embodiment” or “in an embodiment” in various placesthroughout this specification are not necessarily all referring to thesame embodiment, but may. Furthermore, the particular features,structures or characteristics may be combined in any suitable manner, aswould be apparent to a person skilled in the art from this disclosure,in one or more embodiments. Furthermore, while some embodimentsdescribed herein include some but not other features included in otherembodiments, combinations of features of different embodiments are meantto be within the scope of the invention, and form different embodiments,as would be understood by those in the art. For example, in the appendedclaims, any of the claimed embodiments can be used in any combination.

For general methods relating to the invention, reference is made interalia to well-known textbooks, including, e.g., “Molecular Cloning: ALaboratory Manual, 2nd Ed.” (Sambrook et al., 1989), “Current Protocolsin Molecular Biology” (Ausubel et al., 1987).

In an aspect, the invention relates to a nucleic acid regulatory elementfor enhancing muscle-specific gene expression comprising, consistingessentially of (i.e., the regulatory element may for instanceadditionally comprise sequences used for cloning purposes, but theindicated sequences make up the essential part of the regulatoryelement, e.g. they do not form part of a larger regulatory region suchas a promoter), or consisting of a sequence selected from the groupconsisting of: SEQ ID NO:1, SEQ ID NO: 2, SEQ ID NO:3, SEQ ID NO:4, SEQID NO:5, SEQ ID NO:6, SEQ ID NO: 7, SEQ ID NO: 8, SEQ ID NO: 9, SEQ IDNO: 10, SEQ ID NO: 11, SEQ ID NO: 12, SEQ ID NO: 13, a sequence havingat least 80%, preferably at least 85%, more preferably at least 90%,even more preferably at least 95%, such as 95%, 96%, 97%, 98%, or 99%,identity to any of these sequences, or a functional fragment thereof(i.e. a functional fragment of a sequence selected from the groupconsisting of: SEQ ID NO:1, SEQ ID NO: 2, SEQ ID NO:3, SEQ ID NO:4, SEQID NO:5, SEQ ID NO:6, SEQ ID NO: 7, SEQ ID NO: 8, SEQ ID NO: 9, SEQ IDNO: 10, SEQ ID NO: 11, SEQ ID NO: 12, SEQ ID NO: 13, or of a sequencehaving high percentage sequence identity to any of said sequences).

A ‘regulatory element’ as used herein refers to a transcriptionalcontrol element, in particular a non-coding cis-acting transcriptionalcontrol element, capable of regulating and/or controlling transcriptionof a gene, in particular tissue-specific transcription of a gene.Regulatory elements comprise at least one transcription factor bindingsite (TFBS), more in particular at least one binding site for atissue-specific transcription factor, most particularly at least onebinding site for a muscle-specific transcription factor. Typically, toregulatory elements as used herein increase or enhance promoter-drivengene expression when compared to the transcription of the gene from thepromoter alone, without the regulatory elements. Thus, regulatoryelements particularly comprise enhancer sequences, although it is to beunderstood that the regulatory elements enhancing transcription are notlimited to typical far upstream enhancer sequences, but may occur at anydistance of the gene they regulate. Indeed, it is known in the art thatsequences regulating transcription may be situated either upstream (e.g.in the promoter region) or downstream (e.g. in the 3′UTR) of the genethey regulate in vivo, and may be located in the immediate vicinity ofthe gene or further away. Of note, although regulatory elements asdisclosed herein typically comprise naturally occurring sequences,combinations of (parts of) such regulatory elements or several copies ofa regulatory element, i.e. regulatory elements comprising non-naturallyoccurring sequences, are themselves also envisaged as regulatoryelement. Regulatory elements as used herein may comprise part of alarger sequence involved in transcriptional control, e.g. part of apromoter sequence. However, regulatory elements alone are typically notsufficient to initiate transcription, but require a promoter to thisend. The regulatory elements disclosed herein are provided as nucleicacid molecules, i.e. isolated nucleic acids, or isolated nucleic acidmolecules. Said nucleic acid regulatory element hence have a sequencewhich is only a small part of the naturally occurring genomic sequenceand hence is not naturally occurring as such, but is isolated therefrom.

The term “nucleic acid” as used herein typically refers to an oligomeror polymer (preferably a linear polymer) of any length composedessentially of nucleotides. A nucleotide unit commonly includes aheterocyclic base, a sugar group, and at least one, e.g. one, two, orthree, phosphate groups, including modified or substituted phosphategroups. Heterocyclic bases may include inter alia purine and pyrimidinebases such as adenine (A), guanine (G), cytosine (C), thymine (T) anduracil (U) which are widespread in naturally-occurring nucleic acids,other naturally-occurring bases (e.g., xanthine, inosine, hypoxanthine)as well as chemically or biochemically modified (e.g., methylated),non-natural or derivatised bases. Sugar groups may include inter aliapentose (pentofuranose) groups such as preferably ribose and/or2-deoxyribose common in naturally-occurring nucleic acids, or arabinose,2-deoxyarabinose, threose or hexose sugar groups, as well as modified orsubstituted sugar groups. Nucleic acids as intended herein may includenaturally occurring nucleotides, modified nucleotides or mixturesthereof. A modified nucleotide may include a modified heterocyclic base,a modified sugar moiety, a modified phosphate group or a combinationthereof. Modifications of phosphate groups or sugars to may beintroduced to improve stability, resistance to enzymatic degradation, orsome other useful property. The term “nucleic acid” further preferablyencompasses DNA, RNA and DNA/RNA hybrid molecules, specificallyincluding hnRNA, pre-mRNA, mRNA, cDNA, genomic DNA, amplificationproducts, oligonucleotides, and synthetic (e.g., chemically synthesised)DNA, RNA or DNA/RNA hybrids. A nucleic acid can be naturally occurring,e.g., present in or isolated from nature; or can be non-naturallyoccurring, e.g., recombinant, i.e., produced by recombinant DNAtechnology, and/or partly or entirely, chemically or biochemicallysynthesised. A “nucleic acid” can be double-stranded, partly doublestranded, or single-stranded. Where single-stranded, the nucleic acidcan be the sense strand or the antisense strand. In addition, nucleicacid can be circular or linear.

As used herein “transcription factor binding site”, “transcriptionfactor binding sequence” or “TFBS” refers to a sequence of a nucleicacid region to which transcription factors bind. Non-limiting examplesof TFBS include binding sites for transcription factor 3, also known asTCF3 or E2A; binding sites for nuclear factor I, also known as NF1;binding sites for CCAAT-enhancer-binding protein, also known as C/EBP;binding sites for myogenic differentiation, also known as MyoD; bindingsites for sterol regulatory element-binding protein, also known asSREBP; binding sites for leukemia/lymphoma-related factor, also known asLRF; binding sites for protein 53, also known as p53; binding sites forhepatocyte nuclear factor 3-alpha, also known as HNF3a; binding sitesfor hepatocyte nuclear factor 3-beta, also known as HNF3b; binding sitesfor hepatocyte nuclear factor 4, also known as HNF4; binding sites formyocyte-specific enhancer factor 2A, also known as MEF2A or RSRFC4;binding sites for peroxisome proliferator-activated receptor, also knownas PPAR; binding sites for serum response factor, also known as SRF;binding sites for transcription activator-like protein 1b, also known asTal1_b. Transcription factor binding sites may be found in databasessuch as Transfac®.

Sequences disclosed herein may be part of sequences of regulatoryelements capable of controlling transcription of muscle-specific genesin vivo, in particular controlling the following genes: desmin alsoknown as DES, CSM1 or CSM2; actinin, alpha 2 also known as ACTN2 orCMD1AA; filamin-C (FLNC) also known as actin-binding-like protein(ABLP), filamin-2 (FLN2), ABP-280, ABP280A, ABPA, ABPL, MFM5, or MPD4;sarcoplasmic/endoplasmic reticulum calcium ATPase 1 also known asATP2A1, ATP2A, or SERCA1; troponin I type 1 (slow skeletal muscle) alsoknown as TNNI1, SSTNI, or TNN1; myosin light chain phosphorylatable fastskeletal muscle (MYLPF); myosin-1 also known as MYH1, MYHSA1, MYHa;MyHC-2X/D, or MyHC-2x; tropomyosin alpha-3 chain to also known as TPM3,CFTD, NEM1, OK/SW-cl.5, TM-5, TM3, TM30, TM30nm, TM5, TPMsk3, TRK, hTM5,or hscp30; and ankyrin repeat domain-containing protein 2 also known asANKRD2, or ARPP. Accordingly, in embodiments, the nucleic acidregulatory elements disclosed herein comprise a sequence from Desregulatory elements, i.e. regulatory elements that control expression ofthe Des gene in vivo, e.g. regulatory elements comprising SEQ ID NO:1,SEQ ID NO: 17, SEQ ID NO:2, SEQ ID NO:18, or functional fragmentsthereof. In embodiments, the nucleic acid regulatory elements disclosedherein comprise a sequence from ACTN2 regulatory elements, i.e.regulatory elements that control expression of the ACTN2 gene in vivo,e.g. regulatory elements comprising SEQ ID NO:3, SEQ ID NO:19, SEQ IDNO:4, SEQ ID NO:20, or functional fragments thereof. In embodiments, thenucleic acid regulatory elements disclosed herein comprise a sequencefrom FLNC regulatory elements, i.e. regulatory elements that controlexpression of the FLNC gene in vivo, e.g. regulatory elements comprisingSEQ ID NO:5, SEQ ID NO:21, SEQ ID NO:6, SEQ ID NO:22, or functionalfragments thereof. In embodiments, the nucleic acid regulatory elementsdisclosed herein comprise a sequence from ATP2A1 regulatory elements,i.e. regulatory elements that control expression of the ATP2A1 gene invivo, e.g. regulatory elements comprising SEQ ID NO:7, SEQ ID NO:23, orfunctional fragments thereof. In embodiments, the nucleic acidregulatory elements disclosed herein comprise a sequence from TNNI1regulatory elements, i.e. regulatory elements that control expression ofthe TNNI1 gene in vivo, e.g. regulatory elements comprising SEQ ID NO:8,SEQ ID NO:24, SEQ ID NO:9, SEQ ID NO:25, or functional fragmentsthereof. In embodiments, the nucleic acid regulatory elements disclosedherein comprise a sequence from MYLPF regulatory elements, i.e.regulatory elements that control expression of the MYLPF gene in vivo,e.g. regulatory elements comprising SEQ ID NO:10, SEQ ID NO:26, orfunctional fragments thereof, such as regulatory elements comprising orconsisting of SEQ ID NO:37, SEQ ID NO:38, SEQ ID NO:39, SEQ ID NO:40 orSEQ ID NO:41. In embodiments, the nucleic acid regulatory elementsdisclosed herein comprise a sequence from MYH1 regulatory elements, i.e.regulatory elements that control expression of the MYH1 gene in vivo,e.g. regulatory elements comprising SEQ ID NO:11, SEQ ID NO:27, orfunctional fragments thereof. In embodiments, the nucleic acidregulatory elements disclosed herein comprise a sequence from TPM3regulatory elements, i.e. regulatory elements that control expression ofthe TPM3 gene in vivo, e.g. regulatory elements comprising SEQ ID NO:12,SEQ ID NO:28, or functional fragments thereof. In embodiments, thenucleic acid regulatory elements disclosed herein comprise a sequencefrom ANKRD2 regulatory elements, i.e. regulatory elements that controlexpression of the ANKRD2 gene in vivo, e.g. regulatory elementscomprising SEQ ID to NO:13, SEQ ID NO:29, or functional fragmentsthereof.

As used herein, the terms “identity” and “identical” and the like referto the sequence similarity between two polymeric molecules, e.g.,between two nucleic acid molecules, e.g., two DNA molecules. Sequencealignments and determination of sequence identity can be done, e.g.,using the Basic Local Alignment Search Tool (BLAST) originally describedby Altschul et al. 1990 (J Mol Biol 215: 403-10), such as the “Blast 2sequences” algorithm described by Tatusova and Madden 1999 (FEMSMicrobiol Lett 174: 247-250). Typically, the percentage sequenceidentity is calculated over the entire length of the sequence. As usedherein, the term “substantially identical” denotes at least 90%,preferably at least 95%, such as 95%, 96%, 97%, 98% or 99%, sequenceidentity.

The term ‘functional fragment’ as used in the application refers tofragments of the regulatory element sequences disclosed herein thatretain the capability of regulating muscle-specific expression, i.e.they can still confer tissue specificity and they are capable ofregulating expression of a (trans)gene in the same way (althoughpossibly not to the same extent) as the sequence from which they arederived. Functional fragments may preferably comprise at least 20, atleast 25, at least 30, at least 35, at least 40, at least 45, at least50, at least 60, at least 70, at least 80, at least 90, at least 100, atleast 120, at least 150, at least 200, at least 250, at least 300, atleast 350, or at least 400 contiguous nucleotides from the sequence fromwhich they are derived. Also preferably, functional fragments maycomprise at least 1, more preferably at least 2, at least 3, or at least4, even more preferably at least 5, at least 10, or at least 15, of thetranscription factor binding sites (TFBS) that are present in thesequence from which they are derived.

“Muscle-specific expression” as used in the application, refers to thepreferential or predominant expression of a (trans)gene (as RNA and/orpolypeptide) in muscles or muscle tissue, as compared to other (i.e.non-muscle) tissues. According to particular embodiments, at least 50%,more particularly at least 60%, at least 70%, at least 75%, at least80%, at least 85%, at least 90%, at least 95%, at least 98%, at least99% or 100% of the (trans)gene expression occurs within muscle.According to a particular embodiment, muscle-specific expression entailsthat there is no ‘leakage’ of expressed gene product to other organs ortissue than muscle, such as lung, liver, brain, kidney and/or spleen.

As used herein “cardiac and skeletal muscle-specific expression” refersto the preferential or predominant expression of a (trans)gene in heart,in particular heart muscle, and skeletal muscle. According to particularembodiments, at least 50%, more particularly at least 60%, at least 70%,at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, atleast 98%, at least 99% or 100% of the (trans)gene expression occurswithin to heart and skeletal muscle. Thus, according to particularembodiments, less than 10%, less than 5%, less than 2% or even less than1% of the (trans)gene expression occurs in an organ or tissue other thanheart and skeletal muscle.

As used herein “skeletal muscle-specific expression” refers to thepreferential or predominant expression of a (trans)gene in skeletalmuscle. According to particular embodiments, at least 50%, moreparticularly at least 60%, at least 70%, at least 75%, at least 80%, atleast 85%, at least 90%, at least 95%, at least 98%, at least 99% or100% of the (trans)gene expression occurs within skeletal muscle. Thus,according to particular embodiments, less than 10%, less than 5%, lessthan 2% or even less than 1% of the (trans)gene expression occurs in anorgan or tissue other than skeletal muscle.

The same applies mutatis mutandis for myocyte-specific andmyoblast-specific expression, which may be considered as a particularform of muscle-specific expression. Throughout the application, wheremuscle-specific is mentioned in the context of expression,myocyte-specific and myoblast-specific expression are also explicitlyenvisaged. Similarly, where cardiac and skeletal muscle-specificexpression is used in the application, cardiomyocyte and skeletalmyocyte-specific expression and cardiac myoblast and skeletalmyoblast-specific expression is also explicitly envisaged. Similarly,where skeletal muscle-specific expression is used in the application,skeletal myocyte-specific and skeletal myoblast-specific expression isalso explicitly envisaged.

As used herein, the terms “heart muscle” or “cardiac muscle” refer tothe autonomically regulated, striated muscle type found in the heart.

As used herein, the term “skeletal muscle” refers to the voluntarilycontrolled, striated muscle type that is attached to the skeleton.Non-limiting examples of skeletal muscle include the biceps, thetriceps, the quadriceps, the tibialis interior, and the gastrocnemiusmuscle.

The term “myocyte,” as used herein, refers to a cell that has beendifferentiated from a progenitor myoblast such that it is capable ofexpressing muscle-specific phenotype under appropriate conditions.Terminally differentiated myocytes fuse with one another to formmyotubes, a major constituent of muscle fibers. The term “myocyte” alsorefers to myocytes that are de-differentiated. The term includes cellsin vivo and cells cultured ex vivo regardless of whether such cells areprimary or passaged.

The term “myoblast” as used herein, refers to an embryonic cell in themesoderm that differentiates to give rise to a muscle cell or myocyte.The term includes cells in vivo and cells cultured ex vivo regardless ofwhether such cells are primary or passaged.

In embodiments, the invention relates to a nucleic acid regulatoryelement for enhancing muscle-specific gene expression comprising,consisting essentially of, or consisting of a functional fragment of asequence selected from the group consisting of: SEQ ID NO:1, SEQ IDNO:2, SEQ ID NO:3, SEQ ID NO:4, SEQ ID NO:5, SEQ ID NO:6, SEQ ID NO:7,SEQ ID NO:8, SEQ ID NO:9, SEQ ID NO:10, SEQ ID NO:11, SEQ ID NO:12, SEQID NO:13, a sequence having at least 80%, preferably at least 85%, morepreferably at least 90%, even more preferably at least 95%, such as 95%,96%, 97%, 98%, or 99%, identity to any of these sequences, wherein saidfunctional fragment comprises at least 20, preferably at least 25, morepreferably at least 50, at least 100, at least 200 or at least 250,contiguous nucleotides from the sequence from which it is derived, andwherein said functional fragment comprises at least 1, preferably atleast 5, more preferably at least 10 or at least 15, of thetranscription factor binding sites (TFBS) that are present in thesequence from which it is derived.

In further embodiments, the invention relates to a nucleic acidregulatory element for enhancing cardiac and skeletal muscle-specificgene expression comprising a functional fragment of a sequence selectedfrom the group consisting of: SEQ ID NO:1, SEQ ID NO:2, SEQ ID NO:3, SEQID NO:4, SEQ ID NO:5, SEQ ID NO:6, or a sequence having at least 80%,preferably at least 85%, more preferably at least 90%, even morepreferably at least 95%, such as 95%, 96%, 97%, 98%, or 99%, identity toany of these sequences, wherein said functional fragment comprise atleast 20, preferably at least 25, more preferably at least 50, at least100, at least 200 or at least 250, contiguous nucleotides from thesequence from which it is derived, and wherein said functional fragmentcomprises at least 1, preferably at least 5, more preferably at least 10or at least 15, of the transcription factor binding sites (TFBS) thatare present in the sequence from which it is derived.

In yet further embodiments, the invention relates to a nucleic acidregulatory element for enhancing cardiac and skeletal muscle-specificgene expression comprising a functional fragment of a sequence selectedfrom the group consisting of: SEQ ID NO:1 and SEQ ID NO:5, or a sequencehaving at least 80%, preferably at least 85%, more preferably at least90%, even more preferably at least 95%, such as 95%, 96%, 97%, 98%, or99%, identity to any of these sequences, wherein said functionalfragment consists of the nucleotide sequence from position 33 to 58 inSEQ ID NO:1; the nucleotide sequence from position 90 to 142 in SEQ IDNO:1; the nucleotide sequence from position 143 to 233 in SEQ ID NO:1;the nucleotide sequence from position 240 to 310 in SEQ ID NO:1; the tonucleotide sequence from position 90 to 233 in SEQ ID NO:1; thenucleotide sequence from position 47 to 130 in SEQ ID NO:5; thenucleotide sequence from position 252 to 293 in SEQ ID NO:5; or thenucleotide sequence from position 330 to 450 in SEQ ID NO:5.

In further embodiments, the invention relates to a nucleic acidregulatory element for enhancing skeletal muscle-specific geneexpression comprising a functional fragment of a sequence selected fromthe group consisting of: SEQ ID NO:7, SEQ ID NO:8, SEQ ID NO:9, SEQ IDNO:10, SEQ ID NO:11, SEQ ID NO:12, SEQ ID NO:13, a sequence having atleast 80%, preferably at least 85%, more preferably at least 90%, evenmore preferably at least 95%, such as 95%, 96%, 97%, 98%, or 99%,identity to any of these sequences, wherein said functional fragmentcomprise at least 20, preferably at least 25, more preferably at least50, at least 100, at least 200 or at least 250, contiguous nucleotidesfrom the sequence from which it is derived, and wherein said functionalfragment comprises at least 1, preferably at least 5, more preferably atleast 10 or at least 15, of the transcription factor binding sites(TFBS) that are present in the sequence from which it is derived.

In yet further embodiments, the invention relates to a nucleic acidregulatory element for enhancing skeletal muscle-specific geneexpression comprising a functional fragment of SEQ ID NO:10 or asequence having at least 80%, preferably at least 85%, more preferablyat least 90%, even more preferably at least 95%, such as 95%, 96%, 97%,98%, or 99%, identity to SEQ ID NO:10, wherein said functional fragmentconsists of the nucleotide sequence from position 10 to 180 in SEQ IDNO:10; the nucleotide sequence from position 190 to 240 in SEQ ID NO:10;the nucleotide sequence from position 241 to 300 in SEQ ID NO:10; thenucleotide sequence from position 241 to 360 in SEQ ID NO:10; or thenucleotide sequence from position 380 to 420 in SEQ ID NO:10.

In certain embodiments, the nucleic acid regulatory elements of theinvention comprise or consist of a sequence selected from the groupconsisting of: the nucleotide sequence from position 33 to 58 in SEQ IDNO:1; the nucleotide sequence from position 90 to 142 in SEQ ID NO:1;the nucleotide sequence from position 143 to 233 in SEQ ID NO:1; thenucleotide sequence from position 240 to 310 in SEQ ID NO:1; thenucleotide sequence from position 90 to 233 in SEQ ID NO:1; thenucleotide sequence from position 47 to 130 in SEQ ID NO:5; thenucleotide sequence from position 252 to 293 in SEQ ID NO:5; thenucleotide sequence from position 330 to 450 in SEQ ID NO:5; thenucleotide sequence from position 10 to 180 in SEQ ID NO:10; thenucleotide sequence from position 190 to 240 in SEQ ID NO:10; thenucleotide sequence from position 241 to 300 in SEQ ID NO:10; thenucleotide sequence from position 241 to 360 in SEQ ID NO:10; thenucleotide to sequence from position 380 to 420 in SEQ ID NO:10; or asequence having at least 95% identity to any of said sequences.

In certain embodiments, the nucleic acid regulatory elements of theinvention comprise or consist of a sequence selected from the groupconsisting of: the nucleotide sequence from position 33 to 310 in SEQ IDNO:1; the nucleotide sequence from position 47 to 450 in SEQ ID NO:5;the nucleotide sequence from position 10 to 420 in SEQ ID NO:10, or asequence having at least 95% identity to any of said sequences.

In further embodiments, the invention provides a nucleic acid regulatoryelement for enhancing muscle-specific gene expression comprising,consisting essentially of, or consisting of a sequence selected from thegroup consisting of: SEQ ID NO:1, SEQ ID NO:2, SEQ ID NO:3, SEQ ID NO:4,SEQ ID NO:5, SEQ ID NO:6, SEQ ID NO:7, SEQ ID NO:8, SEQ ID NO:9, SEQ IDNO:10, SEQ ID NO:11, SEQ ID NO:12, SEQ ID NO:13, or a sequence having atleast 80%, preferably at least 85%, more preferably at least 90%, evenmore preferably at least 95%, such as 95%, 96%, 97%, 98%, or 99%,identity to any of these sequences.

In yet further embodiments, the invention provides for a nucleic acidregulatory element for enhancing cardiac and skeletal muscle-specificgene expression comprising a sequence selected from the group consistingof: SEQ ID NO:1, SEQ ID NO:2, SEQ ID NO:3, SEQ ID NO:4, SEQ ID NO:5, SEQID NO:6, or a sequence having at least 80%, preferably at least 85%,more preferably at least 90%, even more preferably at least 95%, such as95%, 96%, 97%, 98%, or 99%, identity to any of these sequences.

In yet further embodiments, the invention provides for a nucleic acidregulatory element for enhancing skeletal muscle-specific geneexpression comprising, consisting essentially of, or consisting of asequence selected from the group consisting of: SEQ ID NO:7, SEQ IDNO:8, SEQ ID NO:9, SEQ ID NO:10, SEQ ID NO:11, SEQ ID NO:12, SEQ IDNO:13, or a sequence having at least 80%, preferably at least 85%, morepreferably at least 90%, even more preferably at least 95%, such as 95%,96%, 97%, 98%, or 99%, identity to any of these sequences.

In further embodiments, the nucleic acid regulatory elements forenhancing muscle-specific gene expression, comprise, consist essentiallyof, or consist of a sequence selected from the group consisting of: SEQID NO:17, SEQ ID NO:18, SEQ ID NO:19, SEQ ID NO:20, SEQ ID NO:21, SEQ IDNO:22, SEQ ID NO:23, SEQ ID NO:24, SEQ ID NO:25, SEQ ID NO:26, SEQ IDNO:27, SEQ ID NO:28, SEQ ID NO:29, a functional fragment thereofcomprising SEQ ID NO:1, SEQ ID NO:2, SEQ ID NO:3, SEQ ID NO:4, SEQ IDNO:5, SEQ ID NO:6, SEQ ID NO:7, SEQ ID NO:8, SEQ ID NO:9, SEQ ID NO:10,to SEQ ID NO:11, SEQ ID NO:12, or SEQ ID NO:13, or a sequence having atleast 80%, preferably at least 85%, more preferably at least 90%, evenmore preferably at least 95%, such as 95%, 96%, 97%, 98%, or 99%,identity to any of these sequences.

In further embodiments, the nucleic acid regulatory elements forenhancing cardiac and skeletal muscle-specific gene expression comprise,consist essentially of, or consist of a sequence selected from the groupconsisting of: SEQ ID NO:17, SEQ ID NO:18, SEQ ID NO:19, SEQ ID NO:20,SEQ ID NO:21, SEQ ID NO:22, a functional fragment thereof comprising SEQID NO:1, SEQ ID NO:2, SEQ ID NO:3, SEQ ID NO:4, SEQ ID NO:5, or SEQ IDNO:6, or a sequence having at least 80%, preferably at least 85%, morepreferably at least 90%, even more preferably at least 95%, such as 95%,96%, 97%, 98%, or 99%, identity to any of these sequences.

In further embodiments, the nucleic acid regulatory elements forenhancing skeletal muscle-specific gene expression comprise, consistessentially of, or consist of a sequence selected from the groupconsisting of: SEQ ID NO:23, SEQ ID NO:24, SEQ ID NO:25, SEQ ID NO:26,SEQ ID NO:27, SEQ ID NO:28, SEQ ID NO:29, a functional fragment thereofcomprising SEQ ID NO:7, SEQ ID NO:8, SEQ ID NO:9, SEQ ID NO:10, SEQ IDNO:11, SEQ ID NO:12, or SEQ ID NO:13, or a sequence having at least 80%,preferably at least 85%, more preferably at least 90%, even morepreferably at least 95%, such as 95%, 96%, 97%, 98%, or 99%, identity toany of these sequences.

It is also possible to make nucleic acid regulatory elements thatcomprise an artificial sequence by combining two or more identical ordifferent sequences disclosed herein or functional fragments thereof.Accordingly, in certain embodiments a nucleic acid regulatory elementfor enhancing muscle-specific gene expression is provided comprising atleast two sequences selected from the group consisting of: SEQ ID NO:1,SEQ ID NO:2, SEQ ID NO:3, SEQ ID NO:4, SEQ ID NO:5, SEQ ID NO:6, SEQ IDNO:7, SEQ ID NO:8, SEQ ID NO:9, SEQ ID NO:10, SEQ ID NO:11, SEQ IDNO:12, SEQ ID NO:13, a sequence having at least 90%, preferably at least95%, such as 95%, 96%, 97%, 98%, or 99%, identity to any of thesesequences, or a functional fragment thereof.

Also disclosed herein is a nucleic acid regulatory element for enhancingmuscle-specific gene expression, in particular cardiac and skeletalmuscle-specific gene expression, comprising at least two sequencesselected from the group consisting of: SEQ ID NO:1, SEQ ID NO:2, SEQ IDNO:3, SEQ ID NO:4, SEQ ID NO:5, SEQ ID NO:6, a sequence having at least90%, preferably at least 95%, such as 95%, 96%, 97%, 98%, or 99%,identity to any of these sequences, or a fragment thereof.

Also disclosed herein is a nucleic acid regulatory element for enhancingmuscle-specific to gene expression, in particular skeletalmuscle-specific gene expression, comprising at least two sequencesselected from the group consisting of: SEQ ID NO:7, SEQ ID NO:8, SEQ IDNO:9, SEQ ID NO:10, SEQ ID NO:11, SEQ ID NO:12, SEQ ID NO:13, a sequencehaving at least 90%, preferably at least 95%, such as 95%, 96%, 97%,98%, or 99%, identity to any of these sequences, or a fragment thereof.

For example, disclosed herein is a nucleic acid regulatory elementcomprising, consisting essentially of, or consisting of SEQ ID NO:1 andSEQ ID NO:5; a nucleic acid regulatory element comprising, consistingessentially of, or consisting of SEQ ID NO:1 and SEQ ID NO:10; a nucleicacid regulatory element comprising, consisting essentially of, orconsisting of SEQ ID NO:1, SEQ ID NO:5, and SEQ ID NO:10; a nucleic acidregulatory element comprising, consisting essentially of, or consistingof 2, 3, 4, or 5 repeats, e.g. tandem repeats, of SEQ ID NO:1; a nucleicacid regulatory element comprising, consisting essentially of, orconsisting of 2, 3, 4, or 5 repeats, e.g. tandem repeats, of SEQ IDNO:5; or a nucleic acid regulatory element comprising, consistingessentially of, or consisting of 2, 3, 4, or 5 repeats, e.g. tandemrepeats, of SEQ ID NO:10.

Particular examples of nucleic acid regulatory elements that comprise anartificial sequence include the regulatory elements that are obtained byrearranging the transcription factor binding sites (TFBS) that arepresent in the sequences disclosed herein. Said rearrangement mayencompass changing the order of the TFBSs and/or changing the positionof one or more TFBSs relative to the other TFBSs and/or changing thecopy number of one or more of the TFBSs. For example, also disclosedherein is a nucleic acid regulatory element for enhancingmuscle-specific gene expression, in particular cardiac and skeletalmuscle-specific gene expression, comprising binding sites for E2A, HNH1,NF1, C/EBP, LRF, MyoD, and SREBP; or for E2A, NF1, p53, C/EBP, LRF, andSREBP; or for E2A, HNH1, HNF3a, HNF3b, NF1, C/EBP, LRF, MyoD, and SREBP;or E2A, HNF3a, NF1, C/EBP, LRF, MyoD, and SREBP; or for E2A, HNF3a, NF1,CEBP, LRF, MyoD, and SREBP; or for HNF4, NF1, RSRFC4, C/EBP, LRF, andMyoD, or NF1, PPAR, p53, C/EBP, LRF, and MyoD. For example, alsodisclosed herein is a nucleic acid regulatory element for enhancingmuscle-specific gene expression, in particular skeletal muscle-specificgene expression, comprising binding sites for E2A, NF1, SRFC, p53,C/EBP, LRF, and MyoD; or for E2A, NF1, C/EBP, LRF, MyoD, and SREBP; orfor E2A, HNF3a, C/EBP, LRF, MyoD, SEREBP, and Tal1_b; or for E2A, SRF,p53, C/EBP, LRF, MyoD, and SREBP; or for HNF4, NF1, RSRFC4, C/EBP, LRF,and SREBP; or for E2A, HNF3a, HNF3b, NF1, SRF, C/EBP, LRF, MyoD, andSREBP; or for E2A, CEBP, and MyoD. In further examples, these nucleicacid regulatory elements comprise at least two, to such as 2, 3, 4, ormore copies of one or more of the recited TFBSs.

In case the regulatory element is provided as a single stranded nucleicacid, e.g. when using a single-stranded AAV vector, the complementstrand is considered equivalent to the disclosed sequences. Hence, alsodisclosed herein is a nucleic acid regulatory element for enhancingmuscle-specific gene expression comprising, consisting essentially of,or consisting of the complement of a sequence described herein, inparticular a sequence selected from the group consisting of: SEQ IDNO:1, SEQ ID NO:2, SEQ ID NO:3, SEQ ID NO:4, SEQ ID NO:5, SEQ ID NO:6,SEQ ID NO: 7, SEQ ID NO: 8, SEQ ID NO: 9, SEQ ID NO: 10, SEQ ID NO: 11,SEQ ID NO: 12, SEQ ID NO: 13, a sequence having at least 80%, preferablyat least 85%, more preferably at least 90%, even more preferably atleast 95%, such as 95%, 96%, 97%, 98%, or 99%, identity to any of thesesequences, or a functional fragment thereof.

Also disclosed herein is a nucleic acid regulatory element for enhancingmuscle-specific gene expression hybridizing under stringent conditionsto a nucleic acid regulatory element described herein, in particular tothe nucleic acid regulatory element comprising, consisting essentiallyof, or consisting of a sequence selected from the group consisting of:SEQ ID NO:1, SEQ ID NO: 2, SEQ ID NO:3, SEQ ID NO:4, SEQ ID NO:5, SEQ IDNO:6, SEQ ID NO: 7, SEQ ID NO: 8, SEQ ID NO: 9, SEQ ID NO: 10, SEQ IDNO: 11, SEQ ID NO: 12, SEQ ID NO: 13, a sequence having at least 90%,preferably at least 95%, such as 95%, 96%, 97%, 98%, or 99%, identity toany of these sequences, a functional fragment thereof, or to itscomplement. Said nucleic acid regulatory elements do not need to be ofequal length as the sequence they hybridize to. In preferredembodiments, the size of said hybridizing nucleic acid regulatoryelement does not differ more than 25% in length, in particular 20% inlength, more in particular 15% in length, most in particular 10% inlength from the sequence it hybridizes to.

The expression ‘hybridize under stringent conditions’, refers to theability of a nucleic acid molecule to hybridize to a target nucleic acidmolecule under defined conditions of temperature and salt concentration.Typically, stringent hybridization conditions are no more than 25° C. to30° C. (for example, 20° C., 15° C., 10° C. or 5° C.) below the meltingtemperature (Tm) of the native duplex. Methods of calculating Tm arewell known in the art. By way of non-limiting example, representativesalt and temperature conditions for achieving stringent hybridizationare: 1×SSC, 0.5% SDS at 65° C. The abbreviation SSC refers to a bufferused in nucleic acid hybridization solutions. One liter of the 20×(twenty times concentrate) stock SSC buffer solution (pH 7.0) contains175.3 g sodium chloride to and 88.2 g sodium citrate. A representativetime period for achieving hybridization is 12 hours.

Preferably the regulatory elements as described herein are fullyfunctional while being only of limited length. This allows their use invectors or nucleic acid expression cassettes without unduly restrictingtheir payload capacity. Accordingly, in embodiments, the regulatoryelement disclosed herein is a nucleic acid of 1500 nucleotides or less,1000 nucleotides or less, 900 nucleotides or less, 800 nucleotides orless, 700 nucleotides or less, more preferably 600 nucleotides or less,such as 550 nucleotides or less, 500 nucleotides or less, 450nucleotides or less, 400 nucleotides or less, 350 nucleotides or less,or 300 nucleotides or less (i.e. the nucleic acid regulatory element hasa maximal length of 1500 nucleotides, 1000 nucleotides, 900 nucleotides,800 nucleotides, 700 nucleotides, preferably 600 nucleotides, such as550 nucleotides, 500 nucleotides, 450 nucleotides, 400 nucleotides, 350nucleotides, or 300 nucleotides).

However, it is to be understood that the disclosed nucleic acidregulatory elements retain regulatory activity (i.e. with regard tospecificity and/or activity of transcription) and thus they particularlyhave a minimum length of 20 nucleotides, 25 nucleotides, 30 nucleotides,35 nucleotides, 40 nucleotides, 45 nucleotides, 50 nucleotides, 100nucleotides, 150 nucleotides, 200 nucleotides, 250 nucleotides, 300nucleotides, 350 nucleotides or 400 nucleotides.

In certain embodiments, the invention provides for a nucleic acidregulatory element of 1000 nucleotides or less, preferably 600nucleotides or less, such as 550 nucleotides or less, 500 nucleotides orless, 450 nucleotides or less, 400 nucleotides or less, 350 nucleotidesor less, or 300 nucleotides or less, for enhancing muscle-specific geneexpression comprising a sequence selected from the group consisting of:SEQ ID NO:1, SEQ ID NO: 2, SEQ ID NO:3, SEQ ID NO:4, SEQ ID NO:5, SEQ IDNO:6, SEQ ID NO: 7, SEQ ID NO: 8, SEQ ID NO: 9, SEQ ID NO: 10, SEQ IDNO: 11, SEQ ID NO: 12, SEQ ID NO: 13, a sequence having at least 80%,preferably at least 85%, more preferably at least 90%, even morepreferably at least 95%, such as 95%, 96%, 97%, 98%, or 99%, identity toany of these sequences, or a functional fragment thereof.

The nucleic acid regulatory elements disclosed herein may be used in anucleic acid expression cassette. Accordingly, in an aspect theinvention provides for the use of the nucleic acid regulatory elementsas described herein in a nucleic acid expression cassette.

In an aspect the invention provides a nucleic acid expression cassettecomprising a nucleic acid regulatory element as described herein,operably linked to a promoter. In embodiments, the nucleic acidexpression cassette does not contain a transgene. Such nucleic acidexpression cassette may be used to drive expression of an endogenousgene. In preferred embodiments, the nucleic acid expression cassettecomprises a nucleic acid regulatory element as described herein,operably linked to a promoter and a transgene.

As used herein, the term ‘nucleic acid expression cassette’ refers tonucleic acid molecules that include one or more transcriptional controlelements (such as, but not limited to promoters, enhancers and/orregulatory elements, polyadenylation sequences, and introns) that direct(trans)gene expression in one or more desired cell types, tissues ororgans. Typically, they will also contain a transgene, although it isalso envisaged that a nucleic acid expression cassette directsexpression of an endogenous gene in a cell into which the nucleic acidcassette is inserted.

The term ‘operably linked’ as used herein refers to the arrangement ofvarious nucleic acid molecule elements relative to each such that theelements are functionally connected and are able to interact with eachother. Such elements may include, without limitation, a promoter, anenhancer and/or a regulatory element, a polyadenylation sequence, one ormore introns and/or exons, and a coding sequence of a gene of interestto be expressed (i.e., the transgene). The nucleic acid sequenceelements, when properly oriented or operably linked, act together tomodulate the activity of one another, and ultimately may affect thelevel of expression of the transgene. By modulate is meant increasing,decreasing, or maintaining the level of activity of a particularelement. The position of each element relative to other elements may beexpressed in terms of the 5′ terminus and the 3′ terminus of eachelement, and the distance between any particular elements may bereferenced by the number of intervening nucleotides, or base pairs,between the elements. As understood by the skilled person, operablylinked implies functional activity, and is not necessarily related to anatural positional link. Indeed, when used in nucleic acid expressioncassettes, the regulatory elements will typically be located immediatelyupstream of the promoter (although this is generally the case, it shoulddefinitely not be interpreted as a limitation or exclusion of positionswithin the nucleic acid expression cassette), but this needs not be thecase in vivo. E.g., a regulatory element sequence naturally occurringdownstream of a gene whose transcription it affects is able to functionin the same way when located upstream of the promoter. Hence, accordingto a specific embodiment, the regulatory or enhancing effect of theregulatory element is position-independent.

In particular embodiments, the nucleic acid expression cassettecomprises one nucleic to acid regulatory element as described herein. Inalternative embodiments, the nucleic acid expression cassette comprisestwo or more, such as, e.g., 2, 3, 4, 5, 6, 7, 8, 9, or 10, nucleic acidregulatory elements as described herein, i.e. they are combinedmodularly to enhance their regulatory (and/or enhancing) effect. Infurther embodiments, at least two of the two or more nucleic acidregulatory elements are identical or substantially identical. In yetfurther embodiments, all of the two or more regulatory elements areidentical or substantially identical. The copies of the identical orsubstantially identical nucleic acid regulatory elements may be providedas tandem repeats in the nucleic acid expression cassette. Inalternative further embodiments, at least two of the two or more nucleicacid regulatory elements are different from each other. The nucleic acidexpression cassette may also comprise a combination of identical andsubstantially identical nucleic acid regulatory elements andnon-identical nucleic acid regulatory elements.

For example, the nucleic acid expression cassette may comprise a nucleicacid regulatory element comprising SEQ ID NO:1, and a nucleic acidregulatory element comprising SEQ ID NO:5; or the nucleic acidexpression cassette may comprise a nucleic acid regulatory elementcomprising SEQ ID NO:1 and a nucleic acid regulatory element comprisingSEQ ID NO:10; or the nucleic acid expression cassette may comprise anucleic acid regulatory element comprising SEQ ID NO:1, a nucleic acidregulatory element comprising SEQ ID NO:5, and a nucleic acid regulatoryelement comprising SEQ ID NO:1; or the nucleic acid regulatory elementmay comprise 2, 3, 4, or 5 nucleic acid regulatory elements comprisingSEQ ID NO:1; or the nucleic acid regulatory element may comprise 2, 3,4, or 5 nucleic acid regulatory elements comprising SEQ ID NO:5; or thenucleic acid regulatory element may comprise 2, 3, 4, or 5 nucleic acidregulatory elements comprising SEQ ID NO:10.

As used in the application, the term ‘promoter’ refers to nucleic acidsequences that regulate, either directly or indirectly, thetranscription of corresponding nucleic acid coding sequences to whichthey are operably linked (e.g. a transgene or endogenous gene). Apromoter may function alone to regulate transcription or may act inconcert with one or more other regulatory sequences (e.g. enhancers orsilencers, or regulatory elements). In the context of the presentapplication, a promoter is typically operably linked to a regulatoryelement as disclosed herein to regulate transcription of a (trans)gene.When a regulatory element as described herein is operably linked to botha promoter and a transgene, the regulatory element can (1) confer asignificant degree of muscle-specific, in particular cardiac andskeletal muscle-specific or skeletal muscle-specific, expression in vivo(and/or in myoblasts, myocytes, or muscle-derived cell lines, inparticular cardiac and skeletal or skeletal myoblasts, cardiac andskeletal or skeletal myocytes, or cardiac and skeletal muscle orskeletal muscle-derived cell lines in vitro) of the transgene, and/or(2) can increase the level of expression of the transgene in muscle, inparticular cardiac and skeletal muscle or skeletal muscle (and/or inmyoblasts, myocytes, or muscle-derived cell lines, in particular cardiacand skeletal or skeletal myoblasts, cardiac and skeletal or skeletalmyocytes, or cardiac and skeletal muscle or skeletal muscle-derived celllines in vitro).

The promoter may be homologous (i.e. from the same species as theanimal, in particular mammal, to be transfected with the nucleic acidexpression cassette) or heterologous (i.e. from a source other than thespecies of the animal, in particular mammal, to be transfected with theexpression cassette). As such, the source of the promoter may be anyvirus, any unicellular prokaryotic or eukaryotic organism, anyvertebrate or invertebrate organism, or any plant, or may even be asynthetic promoter (i.e. having a non-naturally occurring sequence),provided that the promoter is functional in combination with theregulatory elements described herein. In preferred embodiments, thepromoter is a mammalian promoter, in particular a murine or humanpromoter.

The promoter may be an inducible or constitutive promoter.

The enrichment in muscle-specific TFBS in the nucleic acid regulatoryelements disclosed herein in principle allows the regulatory elements todirect muscle-specific expression even from a promoter that itself isnot muscle-specific. Hence, the regulatory elements disclosed herein canbe used in nucleic acid expression cassettes in conjunction with theirnatural promoter, as well as with another promoter. Preferably, thenucleic acid expression cassettes disclosed herein comprise amuscle-specific promoter. This to increase muscle-specificity and/oravoid leakage of expression in other tissues. Non-limiting examples ofmuscle-specific promoters, include the desmin (DES) promoter, the alpha2 actinin (ACTN2) promoter, the filamin-C(FLNC) promoter, thesarcoplasmic/endoplasmic reticulum calcium ATPase 1 (ATP2A1) promoter,the troponin I type 1 (TNNI1) promoter, the myosin-1 (MYH1) promoter,the phosphorylatable, fast skeletal muscle myosin light chain (MYLPF)promoter, the alpha-3 chain tropomyosin (TPM3) promoter, the ankyrinrepeat domain-containing protein 2 (ANKRD2) promoter the myosinheavy-chain (MHC) promoter, the myosin light-chain (MLC) promoter, themuscle creatine kinase (MCK) promoter, synthetic muscle promoters asdescribed in Li et al. (1999. Nat Biotechnol. 17:241-245), such as theSPc5-12 promoter, the muscle creatine kinase (MCK) promoter, the dMCKpromoter and the tMCK promoter consisting of respectively, a double ortriple tandem of the MCK enhancer to the MCK basal promoter as describedin Wang et al. (2008. Gene Ther. 15:1489-1499).

In particularly preferred embodiments, the promoter is a mammalianmuscle-specific promoter, in particular a murine or humanmuscle-specific promoter.

In preferred embodiments, the promoter is from the desmin gene, inparticular the murine or human desmin gene, such as the promoter asdefined in SEQ ID NO: 16. For example, the murine desmin promoter iscommercially available as pDRIVE-mDesmin (Invivogen). The desminpromoter is expressed in both cardiac muscle and skeletal muscle.

In embodiments, the promoter is a skeletal muscle-specific promoter, inparticular a muscle creatine kinase (MCK) promoter, more particularlythe double MCK promoter or triple MCK promoter consisting of a double ortriple tandem of MCK enhancer and MCK basal promoter as described inWang et al. (2008. Gene Ther. 15:1489-1499).

Furthermore, the promoter does not need to be the promoter of thetransgene in the nucleic acid expression cassette, although it ispossible that the transgene is transcribed from its own promoter.

To minimize the length of the nucleic acid expression cassette, theregulatory elements may be linked to minimal promoters, or shortenedversions of the promoters described herein. A ‘minimal promoter’ (alsoreferred to as basal promoter or core promoter) as used herein is partof a full-size promoter still capable of driving expression, but lackingat least part of the sequence that contributes to regulating (e.g.tissue-specific) expression. This definition covers both promoters fromwhich (tissue-specific) regulatory elements have been deleted—that arecapable of driving expression of a gene but have lost their ability toexpress that gene in a tissue-specific fashion and promoters from which(tissue-specific) regulatory elements have been deleted that are capableof driving (possibly decreased) expression of a gene but have notnecessarily lost their ability to express that gene in a tissue-specificfashion. Preferably, the promoter contained in the nucleic acidexpression cassette disclosed herein is 1000 nucleotides or less inlength, 900 nucleotides or less, 800 nucleotides or less, 700nucleotides or less, 600 nucleotides or less, 500 nucleotides or less,400 nucleotides or less, 300 nucleotides or less, or 250 nucleotides orless.

The term ‘transgene’ as used herein refers to particular nucleic acidsequences encoding a polypeptide or a portion of a polypeptide to beexpressed in a cell into which the nucleic acid sequence is introduced.However, it is also possible that transgenes are expressed as RNA,typically to control (e.g. lower) the amount of a particular polypeptidein a cell into which the nucleic acid sequence is inserted. These RNAmolecules include but are not limited to molecules that exert theirfunction through RNA interference (shRNA, RNAi), micro-RNA regulation(miR) (which can be used to control expression of specific genes),catalytic RNA, antisense RNA, RNA aptamers, etc. How the nucleic acidsequence is introduced into a cell is not essential to the invention, itmay for instance be through integration in the genome or as an episomalplasmid. Of note, expression of the transgene may be restricted to asubset of the cells into which the nucleic acid sequence is introduced.The term ‘transgene’ is meant to include (1) a nucleic acid sequencethat is not naturally found in the cell (i.e., a heterologous nucleicacid sequence); (2) a nucleic acid sequence that is a mutant form of anucleic acid sequence naturally found in the cell into which it has beenintroduced; (3) a nucleic acid sequence that serves to add additionalcopies of the same (i.e., homologous) or a similar nucleic acid sequencenaturally occurring in the cell into which it has been introduced; or(4) a silent naturally occurring or homologous nucleic acid sequencewhose expression is induced in the cell into which it has beenintroduced.

The transgene may be homologous or heterologous to the promoter (and/orto the animal, in particular mammal, in which it is introduced, e.g. incases where the nucleic acid expression cassette is used for genetherapy).

The transgene may be a full length cDNA or genomic DNA sequence, or anyfragment, subunit or mutant thereof that has at least some biologicalactivity. In particular, the transgene may be a minigene, i.e. a genesequence lacking part, most or all of its intronic sequences. Thetransgene thus optionally may contain intron sequences. Optionally, thetransgene may be a hybrid nucleic acid sequence, i.e., one constructedfrom homologous and/or heterologous cDNA and/or genomic DNA fragments.By ‘mutant form’ is meant a nucleic acid sequence that contains one ormore nucleotides that are different from the wild-type or naturallyoccurring sequence, i.e., the mutant nucleic acid sequence contains oneor more nucleotide substitutions, deletions, and/or insertions. Thenucleotide substitution, deletion, and/or insertion can give rise to agene product (i.e. e., protein or nucleic acid) that is different in itsamino acid/nucleic acid sequence from the wild type amino acid/nucleicacid sequence. Preparation of such mutants is well known in the art. Insome cases, the transgene may also include a sequence encoding a leaderpeptide or signal sequence such that the transgene product will besecreted from the cell.

The transgene that may be contained in the nucleic acid expressioncassettes described herein typically encodes a gene product such as RNAor a polypeptide (protein).

In embodiments, the transgene encodes a therapeutic protein. Thetherapeutic protein may be a secretable protein. Non-limiting examplesof secretable proteins, in particular secretable therapeutic proteins,include clotting factors, such as factor VIII or factor IX, insulin,erythropoietin, lipoprotein lipase, antibodies or nanobodies, growthfactors, to cytokines, chemokines, plasma factors, etc. The therapeuticprotein may also be a structural protein. Non-limiting examples ofstructural proteins, in particular structural therapeutic proteins,include dystrophin and sarcoglycans. In embodiments, the transgenecomprises microdystrophin 1 (MD1) gene or follistatin (FST) gene.

In embodiments, the transgene encodes an immunogenic protein.Non-limiting examples of immunogenic proteins include epitopes andantigens derived from a pathogen.

As used herein, the term “immunogenic” refers to a substance orcomposition capable of eliciting an immune response.

Other sequences may be incorporated in the nucleic acid expressioncassette disclosed herein as well, typically to further increase orstabilize the expression of the transgene product (e.g. introns and/orpolyadenylation sequences).

Any intron can be utilized in the expression cassettes described herein.The term “intron” encompasses any portion of a whole intron that islarge enough to be recognized and spliced by the nuclear splicingapparatus. Typically, short, functional, intron sequences are preferredin order to keep the size of the expression cassette as small aspossible which facilitates the construction and manipulation of theexpression cassette. In some embodiments, the intron is obtained from agene that encodes the protein that is encoded by the coding sequencewithin the expression cassette. The intron can be located 5′ to thecoding sequence, 3′ to the coding sequence, or within the codingsequence. An advantage of locating the intron 5′ to the coding sequenceis to minimize the chance of the intron interfering with the function ofthe polyadenylation signal. In embodiments, the nucleic acid expressioncassette disclosed herein further comprises an intron. Non-limitingexamples of suitable introns are Minute Virus of Mice (MVM) intron,beta-globin intron (betaIVS-II), factor IX (FIX) intron A, Simian virus40 (SV40) small-t intron, and beta-actin intron.

Preferably, the intron is MVM intron.

Any polyadenylation signal that directs the synthesis of a polyA tail isuseful in the expression cassettes described herein, examples of thoseare well known to one of skill in the art. Exemplary polyadenylationsignals include, but are not limited to, polyA sequences derived fromthe Simian virus 40 (SV40) late gene, the bovine growth hormone (BGH)polyadenylation signal, the minimal rabbit β-globin (mRBG) gene, and thesynthetic polyA s(SPA) site as described in Levitt et al. (1989, GenesDev 3:1019-1025) (SEQ ID NO:46).

Preferably, the polyadenylation signal is derived from SV40 (i.e. SV40pA).

In particular embodiments, the invention provides a nucleic acidexpression cassette comprising a nucleic acid regulatory elementconsisting of SEQ ID NO:10 or a sequence having 95% identity to saidsequence, operably linked to a promoter, preferably a promoter selectedfrom the group consisting of the promoter from the desmin gene or theSPc5-12 promoter, and a transgene, preferably a transgene encoding aluciferase. In further embodiments, the nucleic acid expression cassettefurther comprises an MVM intron. In yet further embodiments the nucleicacid expression cassette further comprises a polyadenylation signal,preferably a polyadenylation signal derived from SV40.

In particular embodiments, the invention provides a nucleic acidexpression cassette comprising a nucleic acid regulatory elementconsisting of SEQ ID NO:10 or a sequence having 95% identity to saidsequence, operably linked to a promoter, preferably the promoter fromthe desmin gene, and a transgene, preferably a transgene encodingmicrodystrophin 1 or follistatin. In further embodiments, the nucleicacid expression cassette further comprises an MVM intron. In yet furtherembodiments, the nucleic acid expression cassette further comprises apolyadenylation signal, preferably wherein the polyadenylation signalhas SEQ ID NO:46.

The nucleic acid regulatory element and the nucleic acid expressioncassette disclosed herein may be used as such, or typically, they may bepart of a nucleic acid vector. Accordingly, a further aspect relates tothe use of a nucleic acid regulatory element as described herein or anucleic acid expression cassette as described herein in a vector, inparticular a nucleic acid vector.

In an aspect, the invention also provides a vector comprising a nucleicacid regulatory element as disclosed herein. In further embodiments, thevector comprises a nucleic acid expression cassette as disclosed herein.

The term ‘vector’ as used in the application refers to nucleic acidmolecules, e.g. double-stranded DNA, which may have inserted into itanother nucleic acid molecule (the insert nucleic acid molecule) suchas, but not limited to, a cDNA molecule. The vector is used to transportthe insert nucleic acid molecule into a suitable host cell. A vector maycontain the necessary elements that permit transcribing the insertnucleic acid molecule, and, optionally, translating the transcript intoa polypeptide. The insert nucleic acid molecule may be derived from thehost cell, or may be derived from a different cell or organism. Once inthe host cell, the vector can replicate independently of, orcoincidental with, the host chromosomal DNA, and several copies of thevector and its inserted nucleic acid molecule may be generated. Thevectors can be episomal vectors (i.e., that do not integrate into thegenome of a host cell), or can be vectors that integrate into the hostcell to genome. The term ‘vector’ may thus also be defined as a genedelivery vehicle that facilitates gene transfer into a target cell. Thisdefinition includes both non-viral and viral vectors. Non-viral vectorsinclude but are not limited to cationic lipids, liposomes,nanoparticles, PEG, PEI, plasmid vectors (e.g. pUC vectors, bluescriptvectors (pBS) and pBR322 or derivatives thereof that are devoid ofbacterial sequences (minicircles)) transposons-based vectors (e.g.PiggyBac (PB) vectors or Sleeping Beauty (SB) vectors), etc. Viralvectors are derived from viruses and include but are not limited toretroviral, lentiviral, adeno-associated viral, adenoviral, herpesviral, hepatitis viral vectors or the like. Typically, but notnecessarily, viral vectors are replication-deficient as they have lostthe ability to propagate in a given cell since viral genes essential forreplication have been eliminated from the viral vector. However, someviral vectors can also be adapted to replicate specifically in a givencell, such as e.g. a cancer cell, and are typically used to trigger the(cancer) cell-specific (onco)lysis. Virosomes are a non-limiting exampleof a vector that comprises both viral and non-viral elements, inparticular they combine liposomes with an inactivated HIV or influenzavirus (Yamada et al., 2003). Another example encompasses viral vectorsmixed with cationic lipids.

In preferred embodiments, the vector is a viral vector, such as aretroviral, lentiviral, adenoviral, or adeno-associated viral (AAV)vector, more preferably an AAV vector. AAV vectors are preferably usedas self-complementary, double-stranded AAV vectors (scAAV) in order toovercome one of the limiting steps in AAV transduction (i.e.single-stranded to double-stranded AAV conversion) (McCarty, 2001, 2003;Nathwani et al, 2002, 2006, 2011; Wu et al., 2008), although the use ofsingle-stranded AAV vectors (ssAAV) are also encompassed herein.

AAV serotype 9 (AAV9) is ideally suited to achieve efficienttransduction in heart and skeletal muscle. Accordingly, in particularlypreferred embodiments, the vector is an AAV9 vector, more particularly aself-complementary AAV9 vector (scAAV9).

In other embodiments, the vector is a non-viral vector, preferably aplasmid, a minicircle, or a transposon-based vector, such as a SleepingBeauty (SB)-based vector or piggyBac (PB)-based vector.

In yet other embodiments, the vector comprises viral and non-viralelements.

In particular embodiments, the invention provides a vector comprising anucleic acid expression cassette comprising a nucleic acid regulatoryelement consisting of SEQ ID NO:10, a promoter, preferably the promoterfrom the desmin gene, an MVM intron, a transgene, preferably a transgeneencoding microdystrophin 1, and a polyadenylation signal, preferably thepolyadenylation signal having SEQ ID NO:46. In to particularembodiments, said vector has SEQ ID NO: 44.

In particular embodiments, the invention provides a vector comprising anucleic acid expression cassette comprising a nucleic acid regulatoryelement consisting of SEQ ID NO:10, a promoter, preferably the promoterfrom the desmin gene, an MVM intron, a transgene, preferably a transgeneencoding follistatin, and a polyadenylation signal, preferably thepolyadenylation signal having SEQ ID NO:46. In particular embodiments,said vector has SEQ ID NO: 45.

The nucleic acid expression cassettes and vectors disclosed herein maybe used, for example, to express proteins that are normally expressedand utilized in muscle (i.e. structural proteins), or to expressproteins that are expressed in muscle and that are then exported to theblood stream for transport to other portions of the body (i.e.secretable proteins). For example, the expression cassettes and vectorsdisclosed herein may be used to express a therapeutic amount of a geneproduct (such as a polypeptide, in particular a therapeutic protein, orRNA) for therapeutic purposes, in particular for gene therapy.Typically, the gene product is encoded by the transgene within theexpression cassette or vector, although in principle it is also possibleto increase expression of an endogenous gene for therapeutic purposes.In an alternative example, the expression cassettes and vectorsdisclosed herein may be used to express an immunological amount of agene product (such as a polypeptide, in particular an immunogenicprotein, or RNA) for vaccination purposes.

The nucleic acid expression cassettes and vectors as taught herein maybe formulated in a pharmaceutical composition with a pharmaceuticallyacceptable excipient, i.e., one or more pharmaceutically acceptablecarrier substances and/or additives, e.g., buffers, carriers,excipients, stabilisers, etc. The pharmaceutical composition may beprovided in the form of a kit.

The term “pharmaceutically acceptable” as used herein is consistent withthe art and means compatible with the other ingredients of thepharmaceutical composition and not deleterious to the recipient thereof.

Accordingly, a further aspect of the invention relates to apharmaceutical composition comprising a nucleic acid expression cassetteor a vector described herein.

The use of nucleic acid regulatory elements described herein for themanufacture of these pharmaceutical compositions is also disclosedherein.

In embodiments, the pharmaceutical composition may be a vaccine. Thevaccine may further comprise one or more adjuvants for enhancing theimmune response. Suitable to adjuvants include, for example, but withoutlimitation, saponin, mineral gels such as aluminium hydroxide, surfaceactive substances such as lysolecithin, pluronic polyols, polyanions,peptides, oil or hydrocarbon emulsions, bacilli Calmette-Guerin (BCG),Corynebacterium parvum, and the synthetic adjuvant QS-21. Optionally,the vaccine may further comprise one or more immunostimulatorymolecules. Non-limiting examples of immunostimulatory molecules includevarious cytokines, lymphokines and chemokines with immunostimulatory,immunopotentiating, and pro-inflammatory activities, such asinterleukins (e.g., IL-1, IL-2, IL-3, IL-4, IL-12, IL-13); growthfactors (e.g., granulocyte-macrophage (GM)-colony stimulating factor(CSF)); and other immunostimulatory molecules, such as macrophageinflammatory factor, Flt3 ligand, B7.1; B7.2, etc.

In a further aspect, the invention relates to the nucleic acidregulatory elements, the nucleic acid expression cassettes, the vectors,or the pharmaceutical compositions described herein for use in medicine.

As used herein, the terms “treat” or “treatment” refer to boththerapeutic treatment and prophylactic or preventative measures.Beneficial or desired clinical results include, but are not limited to,prevention of an undesired clinical state or disorder, reducing theincidence of a disorder, alleviation of symptoms associated with adisorder, diminishment of extent of a disorder, stabilized (i.e., notworsening) state of a disorder, delay or slowing of progression of adisorder, amelioration or palliation of the state of a disorder,remission (whether partial or total), whether detectable orundetectable, or combinations thereof. “Treatment” can also meanprolonging survival as compared to expected survival if not receivingtreatment.

As used herein, the terms “therapeutic treatment” or “therapy” and thelike, refer to treatments wherein the object is to bring a subjects bodyor an element thereof from an undesired physiological change or disorderto a desired state, such as a less severe or unpleasant state (e.g.,amelioration or palliation), or back to its normal, healthy state (e.g.,restoring the health, the physical integrity and the physical well-beingof a subject), to keep it at said undesired physiological change ordisorder (e.g., stabilization, or not worsening), or to prevent or slowdown progression to a more severe or worse state compared to saidundesired physiological change or disorder.

As used herein the terms “prevention”, “preventive treatment” or“prophylactic treatment” and the like encompass preventing the onset ofa disease or disorder, including reducing the severity of a disease ordisorder or symptoms associated therewith prior to affliction with saiddisease or disorder. Such prevention or reduction prior to afflictionrefers to administration of the nucleic acid regulatory elements, thenucleic acid expression cassettes, the vectors, or the pharmaceuticalcompositions described herein to a patient that is not at the time ofadministration afflicted with clear symptoms of the disease or disorder.“Preventing” also encompasses preventing the recurrence orrelapse-prevention of a disease or disorder for instance after a periodof improvement. In embodiments, the nucleic acid regulatory elements,the nucleic acid expression cassettes, the vectors, or thepharmaceutical compositions described herein may be for use in genetherapy, in particular muscle-directed gene therapy, more particularlyheart and skeletal muscle-directed gene therapy or skeletalmuscle-directed gene therapy.

Also disclosed herein is the use of the nucleic acid regulatoryelements, the nucleic acid expression cassettes, the vectors, or thepharmaceutical compositions described herein for the manufacture of amedicament for gene therapy, in particular muscle-directed gene therapy,more particularly heart and skeletal muscle-directed gene therapy orskeletal muscle-directed gene therapy.

Also disclosed herein is a method for gene therapy, in particularmuscle-directed gene therapy, more particularly heart and skeletalmuscle-directed gene therapy or skeletal muscle-directed gene therapy,in a subject in need of said gene therapy comprising:

-   -   introducing in the subject, in particular in muscle of the        subject, more particularly in heart muscle or skeletal muscle of        the subject, a nucleic acid expression cassette, a vector or a        pharmaceutical composition described herein, wherein the nucleic        acid expression cassette, the vector or the pharmaceutical        composition comprises a nucleic acid regulatory element        described herein operably linked to a promoter and a transgene;        and    -   expressing a therapeutically effective amount of the transgene        product in the subject, in particular in muscle of the subject,        more particularly in heart and skeletal muscle or in skeletal        muscle of the subject.

The transgene product may be a polypeptide, in particular a structuralprotein such as, e.g., dystrophin or a sarcoglycan, or a secretableprotein such as, e.g., a clotting factor, e.g., factor IX or factorVIII, a cytokine, a growth factor, an antibody or nanobody, a chemokine,a plasma factor, insulin, erythropoietin, lipoprotein lipase. Inparticular embodiments, the transgene product is follistatin ormicrodystrophin, in particular microdystrophin 1. Alternatively, thetransgene product may be RNA, such as siRNA.

Exemplary diseases and disorders that may benefit from gene therapyusing the nucleic acid regulatory elements, the nucleic acid expressioncassettes, the vectors, or the pharmaceutical compositions describedherein include muscular dystrophy (e.g. Duchenne muscular dystrophy(DMD)/Becker muscular dystrophy (BMD)), myotonic dystrophy,neuromuscular disease, motor neuron diseases (MND), such as e.g.Charcot-Marie-Tooth disease (CMT), spinal muscular atrophy (SMA), andamyotrophic lateral sclerosis (ALS), Emery-Dreifuss muscular dystrophy,facioscapulohumeral muscular dystrophy (FSHD), congenital musculardystrophies, congenital myopathies, limb girdle muscular dystrophy,metabolic myopathies, muscle inflammatory diseases, myasthenia,mitochondrial myopathies, anomalies of ionic channels, nuclear envelopdiseases, cardiomyopathies, cardiac hypertrophy, heart failure, distalmyopathies, cardiovascular diseases, hemophilia, including hemophilia Aand B, and diabetes.

Gene therapy protocols have been extensively described in the art. Theseinclude, but are not limited to, intramuscular injection of plasmid(naked or in liposomes), hydrodynamic gene delivery in various tissues,including muscle, interstitial injection, instillation in airways,application to endothelium, intra-hepatic parenchyme, and intravenous orintra-arterial administration. Various devices have been developed forenhancing the availability of DNA to the target cell. A simple approachis to contact the target cell physically with catheters or implantablematerials containing DNA. Another approach is to utilize needle-free,jet injection devices which project a column of liquid directly into thetarget tissue under high pressure. These delivery paradigms can also beused to deliver vectors. Another approach to targeted gene delivery isthe use of molecular conjugates, which consist of protein or syntheticligands to which a nucleic acid- or DNA-binding agent has been attachedfor the specific targeting of nucleic acids to cells (Cristiano et al.,1993). In embodiments, the nucleic acid regulatory elements, the nucleicacid expression cassettes, the vectors, or the pharmaceuticalcompositions described herein may be for use as a vaccine, moreparticularly for use as a prophylactic vaccine.

Also disclosed herein is the use of the nucleic acid regulatoryelements, the nucleic acid expression cassettes, the vectors, or thepharmaceutical compositions described herein for the manufacture of avaccine, in particular for the manufacture of a prophylactic vaccine.

Also disclosed herein is a method of vaccination, in particularprophylactic vaccination, of a subject in need of said vaccinationcomprising:

-   -   introducing in the subject, in particular in muscle of the        subject, more particularly in heart muscle or skeletal muscle of        the subject, a nucleic acid expression cassette, a vector or a        pharmaceutical composition described herein, wherein the nucleic        acid expression cassette, the vector or the pharmaceutical        composition comprises a nucleic acid regulatory element        described herein operably linked to a promoter and a transgene;        and    -   expressing an immunologically effective amount of the transgene        product in the subject, in particular in muscle of the subject,        more particularly in heart and skeletal muscle or in skeletal        muscle of the subject.

As used herein, a phrase such as “a subject in need of treatment”includes subjects that would benefit from treatment of a recited diseaseor disorder. Such subjects may include, without limitation, those thathave been diagnosed with said disease or disorder, those prone tocontract or develop said disease or disorder and/or those in whom saiddisease or disorder is to be prevented.

The terms “subject” and “patient” are used interchangeably herein andrefer to animals, preferably vertebrates, more preferably mammals, andspecifically include human patients and non-human mammals. “Mammalian”subjects include, but are not limited to, humans, domestic animals,commercial animals, farm animals, zoo animals, sport animals, pet andexperimental animals such as dogs, cats, guinea pigs, rabbits, rats,mice, horses, cattle, cows; primates such as apes, monkeys, orang-utans,and chimpanzees; canids such as dogs and wolves; felids such as cats,lions, and tigers; equids such as horses, donkeys, and zebras; foodanimals such as cows, pigs, and sheep; ungulates such as deer andgiraffes; rodents such as mice, rats, hamsters and guinea pigs; and soon. Preferred patients or subjects are human subjects.

A ‘therapeutic amount’ or ‘therapeutically effective amount’ as usedherein refers to the amount of gene product effective to treat a diseaseor disorder in a subject, i.e., to obtain a desired local or systemiceffect. The term thus refers to the quantity of gene product thatelicits the biological or medicinal response in a tissue, system,animal, or human that is being sought by a researcher, veterinarian,medical doctor or other clinician. Such amount will typically depend onthe gene product and the severity of the disease, but can be decided bythe skilled person, possibly through routine experimentation.

An “immunologically effective amount” as used herein refers to theamount of (trans)gene product effective to enhance the immune responseof a subject against a subsequent exposure to the immunogen encoded bythe (trans)gene. Levels of induced immunity can be determined, e.g. bymeasuring amounts of neutralizing secretory and/or serum to antibodies,e.g., by plaque neutralization, complement fixation, enzyme-linkedimmunosorbent, or microneutralization assay.

Typically, the amount of (trans)gene product expressed when using anexpression cassette or vector as described herein (i.e., with at leastone muscle-specific nucleic acid regulatory element) are higher thanwhen an identical expression cassette or vector is used but without anucleic acid regulatory element therein. More particularly, theexpression is at least double as high, at least five times as high, atleast ten times as high, at least 20 times as high, at least 30 times ashigh, at least 40 times as high, at least 50 times as high, or even atleast 60 times as high as when compared to the same nucleic acidexpression cassette or vector without nucleic acid regulatory element.Moreover, the higher expression remains specific to muscle, inparticular both heart and skeletal muscle or skeletal muscle alone.Furthermore, the expression cassettes and vectors described hereindirect the expression of a therapeutic amount of the gene product for anextended period. Typically, therapeutic expression is envisaged to lastat least 20 days, at least 50 days, at least 100 days, at least 200days, and in some instances 300 days or more. Expression of the geneproduct (e.g. polypeptide) can be measured by any art-recognized means,such as by antibody-based assays, e.g. a Western Blot or an ELISA assay,for instance to evaluate whether therapeutic expression of the geneproduct is achieved. Expression of the gene product may also be measuredin a bioassay that detects an enzymatic or biological activity of thegene product. Also disclosed herein is the use of the nucleic acidregulatory elements, the nucleic acid expression cassettes, or thevectors disclosed herein for transfecting or transducing muscle cells,preferably heart muscle cells and/or skeletal muscle cells.

Further disclosed herein is the use of the nucleic acid expressioncassettes or the vectors disclosed herein for expressing a transgeneproduct in muscle cells, preferably heart muscle cells and/or skeletalmuscle cells, wherein the nucleic acid expression cassette or the vectorcomprises a nucleic acid regulatory element disclosed herein operablylinked to a promoter and a transgene.

Further disclosed herein is a method for expressing a transgene productin muscle cells, preferably heart muscle cells and/or skeletal musclecells, comprising:

-   -   transfecting or transducing the muscle cells with a nucleic acid        expression cassette or a vector disclosed herein, wherein the        nucleic acid expression cassette or the vector comprises a        nucleic acid regulatory element disclosed herein operably linked        to a promoter and a transgene; and    -   expressing the transgene product in the muscle cells.

Non-viral transfection or viral vector-mediated transduction of musclecells may be performed by in vitro, ex vivo or in vivo procedures. Thein vitro approach requires the in vitro transfection or transduction ofmuscle cells, e.g. muscle cells previously harvested from a subject,muscle cell lines or muscle cells differentiated from e.g. inducedpluripotent stem cells or embryonic cells. The ex vivo approach requiresharvesting of the muscle cells from a subject, in vitro transfection ortransduction, and optionally re-introduction of the transfected musclecells into the subject. The in vivo approach requires the administrationof the nucleic acid expression cassette or the vector disclosed hereininto a subject. In preferred embodiments, the transfection of the musclecells is performed in vitro or ex vivo.

It is understood by the skilled person that the use of the nucleic acidregulatory elements, the nucleic acid expression cassettes and vectorsdisclosed herein has implications beyond gene therapy, e.g. coaxeddifferentiation of stem cells into myogenic cells, transgenic models forover-expression of proteins in muscle, etc.

The invention is further explained by the following non-limitingexamples

EXAMPLES Example 1: Identification of Cardiac and SkeletalMuscle-Specific Regulatory Elements Experimental Procedures

Genes highly expressed both in heart and muscle, but showing onlyminimal expression in other tissues, were identified using theSpecificity Measure (SPM) method described in Xiao et al. (2010.Bioinformatics 26:1273-1275). As data set we used the U133A/GNF1H GeneAtlas (GSE1133) of the human protein-encoding transcriptomes (Su et al.2004. Proc. Natl. Acad. Sci. USA 101:6062-6067). This resulted in ashort list of 5 genes: filamin-c gene (FLNC), actinin, alpha 2 gene(ACTN2), myosin regulatory light chain 2, ventricular/cardiac muscleisoform gene (MYL2), desmin gene (DES) and telethonin gene (TCAP). Next,the genomic context of these genes was searched for cross-speciesconserved regions enriched for transcription factor binding sites (TFBS)associated with high expression in muscle and heart. Additionalfiltering was done by selecting the putative nucleic acid regulatoryelements that either overlapped or contained regions bearingreproducible biochemical features associated with transcriptionregulation and/or a open chromatin structure as defined in the ENCODEproject (The ENCODE Project Consortium. 2012. Nature 489:57-74).

For the heart-specific regulatory elements we used a high-density geneexpression database of 18,927 unique genes based on microarrays thatwere derived from 158 normal human samples from 19 different organs of30 different individuals (Son, S. et al. 2005. Database of mRNA geneexpression profiles of multiple human organs. Genome Res. 15:443-450).This was used to identify a set of most highly expressed (i.e.‘over-expressed’) genes in the heart compared to any of the othertissues. A two-tailed t-test was used for each pairwise comparison.Conversely, a set of ‘under-expressed’ genes was identified,corresponding to those genes that exhibited the lowest expression inthese respective organs compared to any of the other tissues. Thisanalysis resulted in a set of 43 over-expressed genes and a collectionof 37 under-expressed heart-specific genes. Next, the Reference Sequence(RefSeq) identifiers (IDs) lists of these ‘over-expressed’ and‘under-expressed’ heart-specific genes were used to extract thecorresponding promoter sequences upstream the reported transcriptionstart sites (TSSs) by 1000 bases (NCBI36/hg18 genome assembly), usingthe transcription start location data stored in the refGene table of theUCSC Genome Browser (http://genome.ucsc.edu) database.

This resulted in two sets of heart-specific promoter sequencescorresponding to promoters of ‘over-expressed’ or ‘under-expressed’genes. In order to make a non-redundant set of representative promotersequences, the promoter sequences were filtered using ‘uclust’(http://www.drive5.com/usearch/).

The two sets of non-redundant tissue-specific promoter sequencescorresponding to promoters of ‘over-expressed’ or ‘under-expressed’genes were used as input for the DDM/MDS method, described in detail inDe Bleser et al. (2007. Genome Biol 8:R83), which is specificallyincorporated by reference herein. The observed differential behaviourmight be explained by the presence of one or more TFBS elementscharacteristic of the promoters of the up-regulated or down-regulatedgroup of genes. These ‘differential’ TFBS elements could be found usingfollowing procedure. First, a library of TFBS positional weight matrices(PWMs) (TRANSFAC® 2010.3) was used to predict TFBS on every promotersequence. For the muscle-specific promoters we used the Find IndividualMotif Occurences (fimo) application with a P-value cut-off of 10⁻³. Thenumber of predicted TFBS elements per PWM per promoter was collected inthe form of a matrix in which each row corresponds to a promotersequence, while the columns corresponded to the used PWM. Two TFBS wereconsidered correlated if their corresponding columns in the matrix weresimilar what could be measured using a distance function. With thisapproach, distance matrices summarizing all TFBS associations wereconstructed for the TFBS in both sets of promoters. Finally, bycalculating the distance difference matrix (DDM) and to performingmultidimensional scaling on this DDM to visualize its content in twodimensions, TFBS could be distinguished that did not contribute to theobserved differential gene expression as they were mapped near theorigin of the DDM-MDS plot from ‘deviating’ TFBS that are likelyresponsible for the observed differential gene expression. As the MDSprocedure plots TFBS that are strongly associated closer together thanless associated ones, it was able to highlight interactions between TFBSin the promoter datasets. This procedure resulted in a list of TFBSassociated with high tissue-specific expression for heart-specificpromoters.

For the muscle-specific regulatory elements, a list of muscle-specificgenes was extracted from the Tissue-specific Gene Expression andRegulation (TIGER) database. This was used to identify a set of the mosthighly expressed (i.e. ‘over-expressed’) genes in muscle tissue.Conversely, a set of ‘under-expressed’ genes was identified,corresponding to those genes that exhibited the lowest expression inmuscle. Next, the Reference Sequence (RefSeq) identifiers (IDs) lists ofthese ‘over-expressed’ and ‘under-expressed’ muscle-specific genes wereused to extract the corresponding promoter sequences upstream thereported transcription start sites (TSSs) by 1000 bases (NCBI36/hg18genome assembly), using the transcription start location data stored inthe refGene table of the UCSC Genome Browser (http://genome.ucsc.edu)database. This resulted in two sets of muscle-specific promotersequences corresponding to promoters of ‘over-expressed’ or‘under-expressed’ genes. In order to make a non-redundant set ofrepresentative promoter sequences, the promoter sequences were filteredusing ‘uclust’ (http://www.drive5.com/usearch/).

The two sets of non-redundant tissue-specific promoter sequencescorresponding to promoters of ‘over-expressed’ or ‘under-expressed’genes were used as input for the DDM/MDS method, described in detail inDe Bleser et al. (2007. Genome Biol 8:R83), which is specificallyincorporated by reference herein. The observed differential behaviourmight be explained by the presence of one or more TFBS elementscharacteristic of the promoters of the up-regulated or down-regulatedgroup of genes. These ‘differential’ TFBS elements could be found usingfollowing procedure. First, a library of TFBS positional weight matrices(PWMs) (TRANSFAC® 2010.3) was used to predict TFBS on every promotersequence. For the muscle-specific promoters we used the Find IndividualMotif Occurences (fimo) application with a P-value cut-off of 10⁻³. Thenumber of predicted TFBS elements per PWM per promoter was collected inthe form of a matrix in which each row corresponds to a promotersequence, while the columns corresponded to the used PWM. Two TFBS wereconsidered correlated if their corresponding columns in the matrix towere similar what could be measured using a distance function. With thisapproach, distance matrices summarizing all TFBS associations wereconstructed for the TFBS in both sets of promoters. Finally, bycalculating the distance difference matrix (DDM) and performingmultidimensional scaling on this DDM to visualize its content in twodimensions, TFBS could be distinguished that did not contribute to theobserved differential gene expression as they were mapped near theorigin of the DDM-MDS plot from ‘deviating’ TFBS that are likelyresponsible for the observed differential gene expression. As the MDSprocedure plots TFBS that are strongly associated closer together thanless associated ones, it was able to highlight interactions between TFBSin the promoter datasets. This procedure resulted in a list of TFBSassociated with high tissue-specific expression for muscle-specificpromoters.

Results

This computational approach led to the identification of 6 cardiac andskeletal muscle-specific regulatory sequences, summarized in Table 1.

TABLE 1 Cardiac and skeletal muscle-specific regulatory elements. Bp:base pairs. Gene regulated Size Conserved TFBS Sequence Name by sequence(bp) present SEQ ID NO: 1 CSk-SH1 Des 381 E2A, HNH1, NF1, CEBP, LRF,MyoD, SREBP SEQ ID NO: 2 CSk-SH2 Des 435 E2A, NF1, p53, CEBP, LRF, SREBPSEQ ID NO: 3 CSk-SH3 ACTN2 551 E2A, HNH1, HNF3a, HNF3b, NF1, CEBP, LRF,MyoD, SREBP SEQ ID NO: 4 CSk-SH4 ACTN2 430 E2A, HNF3a, NF1, CEBP, LRF,MyoD, SREBP SEQ ID NO: 5 CSk-SH5 FLNC 454 HNF4, NF1, RSRFC4, CEBP, LRF,MyoD SEQ ID NO: 6 CSk-SH6 FLNC 453 NF1, PPAR, p53, CEBP, LRF, MyoD

Example 2: In Vivo Validation of Cardiac and Skeletal Muscle-SpecificRegulatory Elements Via AAV Vectors Experimental Procedures

Generation of the AAV Plasmid Constructs (pAAV-CSk-SH-Des-Luc2)

The cardiac and skeletal muscle-specific regulatory elements (CSk-SH1 toCSk-SH6) were synthesized by conventional oligonucleotide synthesis andflanked with Acc65I and MluI restriction sites. The different CSk-SHswere cloned upstream of the Desmin (Des) promoter that drives expressionof a Firefly Luciferase (Luc2) reporter gene in the context of anadeno-associated viral vector (AAV) backbone (designated aspAAV-Des-Luc2), to schematically represented in FIG. 3. Thecorresponding AAV plasmid constructs were designated aspAAV-CSk-SH-Des-Luc2. The plasmids also contained a Minute Virus ofMouse (MVM) intron and a Simian Virus 40 (SV40) polyadenylation site(pA).

AAV Vector Production (AAV9sc.CSk-SH1-6.Des.Luc2) and Purification

AAV9 vectors were produced by calcium phosphate (Invitrogen Corp,Carlsbad, Calif.) co-transfection of 293T human embryonic kidney cellswith the pAAV plasmid of interest, an adenoviral helper plasmid and achimeric packaging construct that delivers the AAV2 rep gene togetherwith the AAV9 cap gene, as described in Vandendriessche et al. (2007. JThromb Haemost 5:16-24), which is specifically incorporated by referenceherein.

Briefly, two days post transfection, cells were harvested and vectorparticles were purified using isopycnic centrifugation methods.Harvested cells were lysed by successive freeze/thaw cycles andsonication, treated with benzonase (Novagen, Madison, Wis.) anddeoxycholic acid (Sigma-Aldrich, St. Louis, Mo.) and subsequentlysubjected to 3 successive rounds of cesium chloride (Invitrogen Corp,Carlsbad, Calif.) density gradient ultracentrifugation. Fractionscontaining the AAV vector were collected, concentrated in 1 mM MgCl₂ inDulbecco's phosphate buffered saline (PBS) (Gibco, BRL) and stored at−80° C.

Vector titers (in viral genomes (vg)/ml) were determined by quantitativereal-time PCR using SYBR Green mix (which included SYBR Green dye,Taqman polymerase, ROX and dNTP's all in one) and luciferase specificprimers on an ABI 7500 Real-Time PCR System (Applied Biosystem, Fostercity, CA, USA). The forward and reverse primers used were5′-CCCACCGTCGTATTCGTGAG-3′ (SEQ ID NO: 14) and5′-TCAGGGCGATGGTTTTGTCCC-3′ (SEQ ID NO: 15), respectively.

Typically, for all vectors titers in the range of 1.5-6.1×10¹¹ vg/mlwere achieved from a small production batch of 20 petri dishes ofproducer cells. If higher number of petri dishes such as 60 dishes ofproducer cells were used, a higher titer typically in the range of10¹²-10¹³ gc/ml of AAV particles were achieved. Known copy numbers(10²-10⁷) of the respective vector plasmids used to generate thecorresponding AAV vectors, carrying the appropriate cDNAs were used togenerate the standard curves.

Animal Studies

All animal procedures were approved by the institutional animal ethicscommittee of the Free University of Brussels (VUB) (Brussels, Belgium).All mice were housed under specific pathogen-free conditions; food andwater were provided ad libitum.

Two-days old CB.17/IcrTac/Prkdcscid mice were intravenously injectedinto the periorbital vein with 50 μl of concentrated vectors (5×10⁹vg/mouse) containing the different CSk-SH (i.e. CSk-SH1 to CSk-SH6)regulatory elements or AAV9-Des-Luc2 control vector (5×10⁹ vg/mouse) assummarized in Table 2.

TABLE 2 Experimental design for the injection of cardiac and skeletalmuscle-specific regulatory elements. Mouse number Titre Volume VolumeTotal Vector (n) Dose (gc/ml) vector (μl) PBS (μl) volume (μl) AAV9sc. 35 × 10⁹ 5.7 × 10¹¹ 8.7 41.3 50 Des.Luc2 AAV9sc.CSk- 4 5 × 10⁹ 6.1 × 10¹¹8.2 41.8 50 SH1.Des.Luc2 AAV9sc.CSk- 2 5 × 10⁹ 6.0 × 10¹¹ 8.3 41.7 50SH2.Des.Luc2 AAV9sc.CSk- 5 5 × 10⁹ 1.5 × 10¹¹ 33.3 16.7 50 SH3.Des.Luc2AAV9sc.CSk- 3 5 × 10⁹ 5.2 × 10¹¹ 9.6 40.4 50 SH4.Des.Luc2 AAV9sc.CSk- 45 × 10⁹ 1.7 × 10¹¹ 39.4 20.6 50 SH5.Des.Luc2 AAV9sc.CSk- 4 5 × 10⁹ 3.1 ×10¹¹ 16.1 33.9 50 SH6.Des.Luc2

Mice were imaged between 5 and 8 weeks post-injection once per weekusing a biospace In Vivo photo Imaging System (IVIS). The CCD was cooledto −120° C. and the field of view (FOV) set at 25 cm height of thesample shelf. The charged coupled device (CCD) camera operates byconverting photons that strike the CCD pixel into electrons atwavelengths between 400-100 nm, allowing detection of visible imagedinfrared light through by anesthetizing with 2% isofluorane and oxygen.D-luciferin substrate was injected intravenously, at a dose of 150 μg/gof body weight. Mice were euthanized 9 weeks post injection and intactorgans were harvested and imaged using a biospace In Vivo photo toImaging System (IVIS).

mRNA Analysis

Total RNA was extracted from different organs of the mice by asilica-membrane based purification kit according to the manufacturer'sinstructions (Invitrogen Corp, Carlsbad, Calif., USA). Subsequently, 50ng of total RNA from each sample was subjected to reverse transcription(RT) using a cDNA synthesis kit (Invitrogen Corp, Carlsbad, Calif.,USA). Next, a cDNA amount corresponding to 10 ng of total RNA wasamplified by quantitative (q) PCR on an ABI 7700 (Applied Biosystems,Foster City, Calif., USA), using 5′-CCCACCGTCGTATTCGTGAG-3′ (SEQ ID NO:14) as a forward primer and 5′-TCAGGGCGATGGTTTTGTCCC-3′ (SEQ ID NO: 15)as reverse primer (amplicon 217 bp). The qPCR standards consisted ofserially diluted AAV9-CSk-SH-Des-Luc2 plasmids of known quantity. TheLuc2 mRNA levels were normalized to mRNA levels of the endogenous murineglyceraldehyde-3-phosphate dehydrogenase (mGAPDH) gene, using5′-TGTGTCCGTCGTGGATCTGA-3′ (SEQ ID NO:31) as forward primer and5′-GCCTGCTTCACCACCTTCTTGA-3′ (SEQ ID NO:32) as the reverse primer(amplicon 82 bp). RNA samples were amplified with and without reversetranscriptase to exclude DNA amplification. The size of the amplifiedPCR fragments was verified on a 1.8% agarose gel.

Transduction Efficiency and Vector Biodistribution

Transduction efficiency of the viral vectors and biodistribution wereevaluated by quantifying Luc2 transgene copy numbers in the differentorgans and tissues as described previously (Pacak, C. A., et al. 2008.Genet Vaccines Ther 6: 13). Briefly, genomic DNA to was extracted from30 mg of each tissue according to DNeasy Blood & Tissue Kit protocol(Qiagen, Chatsworth, Calif., USA) and 100 ng of genomic DNA from eachsample was subjected to qPCR, using the Luc2-specific forward primer5′-CCCACCGTCGTATTCGTGAG-3′ (SEQ ID NO: 14) and reverse primer5′-TCAGGGCGATGGTTTTGTCCC-3′ (SEQ ID NO: 15) (amplicon 217 bp). Knowncopy numbers (10²-10⁷) of the corresponding plasmid pAAV-CSk-SH-Des-Luc2were used to generate the standard curve. The results were expressed asmean AAV copy number/100 ng of genomic DNA.

Results

To assess the effect of the in silico identified cardiac and skeletalmuscle-specific regulatory elements (CSk-SH) in vivo, adeno-associatedvectors were generated that expressed the luciferase gene luc2 from achimeric promoter. This promoter was composed of the muscle-specificdesmin (Des) promoter linked to the cardiac and skeletal muscle-specificregulatory elements CSk-SH1-6. The vectors were intravenously injectedin mice and whole body images were taken from the mice at 5 and 6 weekspost-injection to examine luciferase expression level.

All mice injected with a vector comprising a cardiac and skeletalmuscle-specific regulatory element (CSk-SH1-6) showed increasedluciferase activity compared to control mice that were injected with acorresponding AAV9 vector without a regulatory element, indicating thatall of the regulatory elements tested increased luciferase expression(data not shown). We observed very robust and enhanced luciferaseactivity in mice that were injected with AAV9 vector comprising theregulatory element CSk-SH1, CSk-SH3 or CSk-SH5 at 5 and 6 weekspost-injection as compared to luciferase activity of the control mice.

We also determined luciferase activity in the individual organs. Nineweeks post injection, the mice were euthanized and individual organswere analyzed to evaluate luciferase expression and the biodistributionpattern. We observed significantly increased levels of luciferaseactivity in the heart, the biceps, the triceps, the quadriceps, thetibialis interior, and the gastrocnemius muscle of mice injected withAAV vector comprising a regulatory element CSk-SH1-6 as compared tocontrol mice. Up to 48-fold augmentation of luciferase activity wasmeasured in the heart of mice injected with AAV vector comprising theCSk-SH5 regulatory element as compared to control mice (FIG. 4A). Thisregulatory element was also the most robust in muscle, in particulargastrocnemius muscle, tibialis to interior, quadriceps, biceps andtriceps. Hence, the most potent regulatory element was CSk-SH5. Thesecond most robust regulatory element was CSk-SH1. A 25-foldaugmentation of luciferase activity was measured in the heart of miceinjected with AAV vector comprising CSK-SH1 when compared to controlmice. Robust luciferase activity was also measured in other muscle ofmice injected with CSk-SH1. The third robust regulatory element wasCSk-SH3, followed by CSk-SH6, CSk-SH4 and CSk-SH2. Furthermore theexpression was specific for cardiac and skeletal muscle as luciferaseexpression was absent or limited in all other organs (FIG. 5A), despitetransduction of the vector into the other organs (FIG. 6A-B). The levelof luciferase activity measured in the organs was consistent with theluciferase mRNA levels measured in the respective organs (FIG. 4B, 5B).These in vivo data show that the nucleic acid regulatory elementsCSk-SH, in particular CSk-SH1, CSk-SH3 and CSk-SH5, more particularlyCSk-SH1 and Csk-SH5, can enhance heart and skeletal muscle-specificluciferase expression.

Example 3: Identification of Skeletal Muscle-Specific RegulatoryElements Experimental Procedures

First, a list of muscle-specific genes was extracted from theTissue-specific Gene Expression and Regulation (TIGER) database. Thiswas used to identify a set of the most highly expressed (i.e.‘over-expressed’) genes in muscle tissue. Conversely, a set of‘under-expressed’ genes was identified, corresponding to those genesthat exhibited the lowest expression in muscle. Next, the ReferenceSequence (RefSeq) identifiers (IDs) lists of these ‘over-expressed’ and‘under-expressed’ muscle-specific genes were used to extract thecorresponding promoter sequences upstream the reported transcriptionstart sites (TSSs) by 1000 bases (NCBI36/hg18 genome assembly), usingthe transcription start location data stored in the refGene table of theUCSC Genome Browser (http://genome.ucsc.edu) database. This resulted intwo sets of muscle-specific promoter sequences corresponding topromoters of ‘over-expressed’ or ‘under-expressed’ genes. In order tomake a non-redundant set of representative promoter sequences, thepromoter sequences were filtered using ‘uclust’(http://www.drive5.com/usearch/).

The two sets of non-redundant tissue-specific promoter sequencescorresponding to promoters of ‘over-expressed’ or ‘under-expressed’genes were used as input for the DDM/MDS method, described in detail inDe Bleser et al. (2007. Genome Biol 8:R83), which is specificallyincorporated by reference herein. The observed differential behaviourmight be explained by the presence of one or more TFBS elementscharacteristic of the promoters of the up-regulated or down-regulatedgroup of genes. These ‘differential’ TFBS elements could be found usingfollowing procedure. First, a library of TFBS positional to weightmatrices (PWMs) (TRANSFAC® 2010.3) was used to predict TFBS on everypromoter sequence. For the muscle-specific promoters we used the FindIndividual Motif Occurences (fimo) application with a P-value cut-off of10⁻³. The number of predicted TFBS elements per PWM per promoter wascollected in the form of a matrix in which each row corresponds to apromoter sequence, while the columns corresponded to the used PWM. TwoTFBS were considered correlated if their corresponding columns in thematrix were similar what could be measured using a distance function.With this approach, distance matrices summarizing all TFBS associationswere constructed for the TFBS in both sets of promoters. Finally, bycalculating the distance difference matrix (DDM) and performingmultidimensional scaling on this DDM to visualize its content in twodimensions, TFBS could be distinguished that did not contribute to theobserved differential gene expression as they were mapped near theorigin of the DDM-MDS plot from ‘deviating’ TFBS that are likelyresponsible for the observed differential gene expression. As the MDSprocedure plots TFBS that are strongly associated closer together thanless associated ones, it was able to highlight interactions between TFBSin the promoter datasets. This procedure resulted in a list of TFBSassociated with high tissue-specific expression for muscle-specificpromoters.

Next, the genomic context of the tissue-specific over-expressed geneswas searched for cross-species conserved regions for the TFBS associatedwith high tissue-specific gene expression. For that purpose, thesequences of all conserved sequence elements in the NCBI36/hg18 genomeassembly were downloaded based on the information stored in thephastConsElements44way table of the UCSC Genome Browser(http://genome.ucsc.edu) database. The predicted conserved sequenceelements are assigned a log-odds score equal to its log probabilityunder the conserved model minus its log probability under thenon-conserved model. This allows to restrict the search for putativeregulatory elements that coincide with the most conserved sequenceelements. The conserved sequence elements were scanned for TFBSassociated with high tissue-specific expression using the fimoapplication, as described above. Using internally developed Perlscripts, this led to the identification of highly conserved sequenceelements containing clusters of TFBS associated with hightissue-specific expression (i.e. nucleic acid regulatory elements).Additional filtering was done by selecting the putative nucleic acidregulatory elements that either overlapped or contained regions bearingreproducible biochemical features associated with transcriptionregulation and/or a open chromatin structure as defined in the ENCODEproject (The ENCODE Project Consortum. 2012. Nature 489:57-74).

Results

This computational approach led to the identification of 6muscle-specific regulatory sequences, summarized in Table 3.

TABLE 3 Muscle-specific regulatory elements. Bp: base pairs. Generegulated Size Conserved Sequence Name by sequence (bp) TFBS present SEQID NO: 7 Sk-SH1 ATP2A1 495 E2A, NF1, SRFC, p53, CEBP, LRF, MyoD SEQ IDNO: 8 Sk-SH2 TNNI1 344 E2A, NF1, CEBP, LRF, MyoD, SREBP SEQ ID NO: 9Sk-SH3 TNNI1 430 E2A, HNF3a, CEBP, LRF, MyoD, SREBP, Tal1_b SEQ ID NO:10 Sk-SH4 MYLPF 435 E2A, SRF, p53, CEBP, LRF, MyoD, SREBP SEQ ID NO: 11Sk-SH5 MYH1 474 HNF4, NF1, RSRFC4, CEBP, LRF, SREBP SEQ ID NO: 12 Sk-SH6TPM3 519 E2A, HNF3a, HNF3b, NF1, SRF, CEBP, LRF, MyoD, SREBP SEQ ID NO:13 Sk-SH7 ANKRD2 372 E2A, CEBP, MyoD

Example 4: In Vivo Validation of Skeletal Muscle-Specific RegulatoryElements Via AAV Vectors Comprising a Desmin Promoter ExperimentalProcedures

AAV plasmid constructs comprising a skeletal muscle-specific regulatoryelement (pAAV-Sk-SH-Des-Luc2) were generated according to the protocoldescribed in Example 2. Briefly, the skeletal muscle-specific regulatoryelements were synthesized by conventional oligonucleotide synthesis andflanked with Acc65I and MluI restriction sites (Sk-SH1, 2, 3, 4, 5 and7) or BsiWI and MluI restriction sites (Sk-SH6). The different Sk-SHswere cloned upstream of the Desmin (Des) promoter that drives expressionof a Firefly Luciferase (Luc2) reporter gene in the context of the AAVvector backbone pAAV-Des-Luc2. The plasmids also contained a MinuteVirus of Mouse (MVM) intron and a Simian Virus 40 (SV40) polyadenylationsite (pA).

AAV vector production and purification and animal studies were carriedout as described in Example 2. The experimental design is summarized inTable 4.

TABLE 4 Experimental design for the injection of skeletalmuscle-specific regulatory elements. Mouse number Titre Volume VolumeTotal Vector (n) Dose (gc/ml) vector (μl) PBS (μl) volume (μl) AAV9sc. 55 × 10⁹ 5.7 × 10¹¹ 8.7 41.3 50 Des.Luc2 AAV9sc. Sk- 4 5 × 10⁹ 1.7 × 10¹¹29.4 20.6 50 SH1.Des.Luc2 AAV9sc. Sk- 4 5 × 10⁹ 1.8 × 10¹¹ 27.7 22.3 50SH2.Des.Luc2 AAV9sc. Sk- 4 5 × 10⁹ 1.9 × 10¹¹ 26.3 23.7 50 SH3.Des.Luc2AAV9sc. Sk- 4 5 × 10⁹ 1.6 × 10¹¹ 31.3 18.7 50 SH4.Des.Luc2 AAV9sc. Sk- 15 × 10⁹ 8.1 × 10¹¹ 62 3 65 SH5.Des.Luc2 AAV9sc. Sk- 3 5 × 10⁹ 1.410¹¹35.7 14.3 50 SH6.Des.Luc2 AAV9sc. Sk- 4 5 × 10⁹ 1.8 × 10¹¹ 27.7 22.3 50SH7.Des.Luc2

mRNA analysis and transduction efficiency and vector biodistributionwere assessed as described in Example 2.

Results

Adeno-associated vectors were generated that expressed the luciferasegene luc2 from a chimeric promoter composed of the desmin (Des) promoterlinked to the skeletal muscle-specific regulatory elements Sk-SH1-7. Thevectors were intravenously injected in mice and whole body images weretaken from the mice at 5 and 6 weeks post-injection to examineluciferase expression level.

All mice injected with a vector comprising a skeletal muscle-specificregulatory element (Sk-SH1-7) showed increased luciferase activitycompared to control mice that were injected with a corresponding AAV9vector without a regulatory element, indicating that all of theregulatory elements tested increased luciferase expression from thedesmin promoter (data not shown). We observed very robust and enhancedluciferase activity in mice that were injected with AAV9 vectorcomprising the regulatory element Sk-SH1 or Sk-SH4 at 5 and 6 weekspost-injection as compared to luciferase activity of the control mice.

7 weeks post injection, the mice were euthanized and individual organswere analyzed to evaluate luciferase expression and the biodistributionpattern (FIGS. 8 and 9). Up to 200 to 400-fold augmentation ofluciferase activity was measured in skeletal muscle, in particulargastrocnemius muscle, tibialis interior, quadriceps, biceps and triceps,of mice injected with AAV vector comprising the Sk-SH4 regulatoryelement as compared to control mice (FIG. 8). There was still a 36-foldaugmentation of luciferase activity measured in the heart of said mice(FIG. 8), due to the use of the desmin promoter, which is specific forboth, heart and skeletal muscle. Luciferase expression was absent orlimited in all other organs than cardiac and skeletal muscle tissue(FIG. 9). The second most robust regulatory element was Sk-SH1, whichalso specifically increased luciferase expression from the desminpromoter in skeletal muscle, and to a lesser extent in heart muscle.

The level of luciferase activity measured in the heart and differentskeletal muscles was consistent with the luciferase mRNA levels measuredin the respective organs (FIG. 12). Notwithstanding the transduction ofthe vector into different organs as shown in FIG. 13, luciferaseexpression was absent or limited in all other organs than cardiac andskeletal muscle tissue (FIG. 9).

These in vivo data show that the nucleic acid regulatory elements Sk-SH,in particular Sk-SH1 and Sk-SH4, can enhance heart and skeletalmuscle-specific luciferase expression.

The nucleic acid regulatory element Sk-SH4 is by far the most robustelement that led to the highest level of luciferase expression in theheart and skeletal muscle as compared to the other 5 regulatory elementsthat were identified. The highest activity that we measured was a400-fold upregulation of luciferase activity in the tibialis.

Example 5: In Vivo Comparison of Muscle-Specific Regulatory Elements andCMV Promoter Experimental Procedures

AAV plasmid constructs comprising a muscle-specific regulatory element(pAAV-Sk-SH4-Des-Luc2, pAAV-CSk-SH1-Des-Luc2, pAAV-CSk-SH5-Des-Luc2)were generated to according to the protocol described in Example 2.Briefly, the muscle-specific regulatory elements were synthesized byconventional oligonucleotide synthesis and cloned upstream of the Desmin(Des) promoter that drives expression of a Firefly Luciferase (Luc2)reporter gene in the context of the AAV vector backbone pAAV-Des-Luc2.The plasmids also contained a Minute Virus of Mouse (MVM) intron and aSimian Virus 40 (SV40) polyadenylation site (pA).

A pAAVsc-CMV-Luc2-SV40 pA plasmid construct was generated, wherein theCytomegalovirus (CMV) promoter (SEQ ID NO: 30) is cloned upstream theFirefly Luciferase (Luc2) reporter gene instead of the desmin promoterin the context of the AAV vector backbone pAAV-Des-Luc2. The plasmidalso contained a Simian Virus 40 (SV40) polyadenylation site (pA). Aschematic representation of pAAVsc-CMV-Luc2-SV40 pA is shown in FIG.10A. For the cloning of the AAVsc-CMV-Luc2-SV40 pA, the fragment5′-Acc65I-CMV-HindIII-3′ was synthesised and cloned into anAAVsc-Luc2-SV40 pA vector which was restricted with the same pair ofenzymes (i.e. Acc65I and HindIII).

AAV vector production and purification were carried out as described inExample 2.

6 weeks old male CB17 SC SCID mice having an average weight of 17.4±1.6g were intravenously injected into the periorbital vein with 1×10¹⁰vg/mouse of concentrated vectors. Mice were imaged 4 weekspost-injection as described in Example 2. Mice were euthanized 5 weekspost-injection and intact organs were harvested and imaged as describedin Example 2.

Results

Luciferase activity was compared in mice that were injected with avector that expressed the luciferase gene luc2 from the desmin (Des)promoter operably linked to a muscle-specific regulatory element:SK-SH4, CSk-SH1 or CSk-5H5, versus mice that were injected with a vectorthat expressed the luciferase gene luc2 from the Cytomegalovirus (CMV)promoter. The CMV promoter is considered one of the most powerfulpromoters known to allow robust gene expression in the heart. Nomuscle-specific regulatory element was present in the latter vectors.

FIGS. 10A and 10B show that the vectors comprising a muscle-specificregulatory element of the invention operably linked to the desminpromoter allow for much better expression than the vector comprising theCMV promoter.

Example 6: In Vivo Validation of Skeletal Muscle-Specific RegulatoryElements Via Vectors Comprising a Skeletal Muscle-Specific PromoterExperimental Procedures

AAV plasmids are constructed as described in Example 4, wherein thedesmin promoter is replaced by the muscle-specific promoter described inWang et al. (2008. Gene Ther. 15:1489-1499).

AAV vector production and purification and animal studies are carriedout as described in Example 2.

Results

When using a skeletal muscle-specific promoter instead of the desminpromoter, the increase in luciferase expression is confined to skeletalmuscle only, showing that the nucleic acid regulatory elements Sk-SH1-7,in particular Sk-SH4 and Sk-SH1 enhance skeletal muscle-specificluciferase expression.

Example 7: In Vivo Validation of Functional Fragments of the IdentifiedMuscle-Specific Regulatory Elements Experimental Procedures

The identified nucleic acid regulatory elements CSk-SH1 (SEQ ID NO: 1;381 bp), CSk-SH5 (SEQ ID NO:5; 454 bp) and Sk-SH4 (SEQ ID NO:10; 435 bp)were split into smaller functional fragments. The transcription factorbinding sites (TFBS) of the regulatory elements were mapped on therespective sequence (FIG. 11A-C), and functional fragments weregenerated by randomly clustering regions with TFBS. The followingfunctional fragments were generated:

Functional Fragments of SEQ ID NO:1:

Cluster 1A: the nucleotide sequence from position 33 to 58 in SEQ IDNO:1

Cluster 1B: the nucleotide sequence from position 90 to 142 in SEQ IDNO:1

Cluster 1C: the nucleotide sequence from position 143 to 233 in SEQ IDNO:1

Cluster 1D: the nucleotide sequence from position 240 to 310 in SEQ IDNO:1

Cluster 1E: the nucleotide sequence from position 90 to 233 in SEQ IDNO:1

Functional Fragments of SEQ ID NO:5:

Cluster 5A: the nucleotide sequence from position 47 to 130 in SEQ IDNO:5

Cluster 5B: the nucleotide sequence from position 252 to 293 in SEQ IDNO:5

Cluster 5C: the nucleotide sequence from position 330 to 450 in SEQ IDNO:5

Functional Fragments of SEQ ID NO:10:

Cluster 4A: the nucleotide sequence from position 10 to 180 in SEQ IDNO:10 (SEQ ID NO: 37);

Cluster 4B: the nucleotide sequence from position 190 to 240 in SEQ IDNO:10 (SEQ ID NO: 38);

Cluster 4C: the nucleotide sequence from position 241 to 300 in SEQ IDNO:10 (SEQ ID NO: 39);

Cluster 4E: the nucleotide sequence from position 241 to 360 in SEQ IDNO:10 (SEQ ID NO:41)

Cluster 4D: the nucleotide sequence from position 380 to 420 in SEQ IDNO:10 (SEQ ID NO: 40)

The functional fragments of Sk-SH4 are summarized in Table 5.

TABLE 5 Functional fragments of the muscle-specific regulatory elementSk-SH4. Bp: base pairs. Gene regulated Size Conserved TFBS Sequence Nameby sequence (bp) present SEQ ID NO: 37 Sk-SH4^(a) MYLPF 171 CEBP, E2A,LRF, SRFb, SRFc SEQ ID NO: 38 Sk-SH4^(b) MYLPF  51 CEBP, E2A, LRF, SRFbSEQ ID NO: 39 Sk-SH4^(c) MYLPF  60 E2A, LRF, SRFb, MyoD SEQ ID NO: 40Sk-SH4^(d) MYLPF  41 LRF, SRFb, p53, MyoD SEQ ID NO: 41 Sk-SH4^(e) MYLPF120 CEBP, E2A, LRF, SRFb

The functional fragments of Sk-SH4 were synthesized by conventionaloligonucleotide synthesis and cloned into the pAAV9sc-Des-Luc2 vector asdescribed in Example 2. AAV vector production and purification werecarried out as described in Example 2. 6 weeks old CB17/IcrTac/Prkdcscid adult mice with an average weight of about 17-18 g per mouse wereintravenously injected with the AAV vectors at a dose of 1×10¹⁰ vg permouse. After 2 and 4 weeks post injection, the mice were subjected toimaging using the same biospace In Vivo photo Imaging System asdescribed in Example 2.

Results

The results shown in FIG. 14 show that all 5 fragments of the Sk-SH4regulatory element were capable of augmenting the expression of theluciferase gene driven from the desmin promoter when compared to thereference construct without any regulatory element. The fragmentSk-SH4^(b) showed the highest luciferase expression compared to theother fragments. However, none of the fragments could achieve higher orequal luciferase to expression when compared to the expression inducedby the full length Sk-SH4 fragment.

Example 8: In Vivo Validation of Modules of Muscle-Specific RegulatoryElements

The muscle-specific regulatory elements are further validated by makingdifferent combinations of the regulatory elements and/or by usingseveral copies of the same regulatory element (e.g. CSk-SH1 combinedwith CSk-SH5; CSk-SH1 combined with Sk-SH4; CSk-SH1 combined withCSk-SH5 and SkSH4; CSk-SH1 repeated 3× or 4×; CSk-SH5 repeated 3× or 4×;Sk-SH4 repeated 3× or 4×). These constructs are incorporated upstream ofthe Des promoter in accordance with the protocol described in Example 2.AAV vector production and purification and animal studies are carriedout as described in Example 2.

Further combinations are made with functional fragments of theidentified muscle-specific regulatory elements as generated in Example7.

Example 9: Binding of Transcription Factors to Muscle-SpecificRegulatory Elements Experimental Procedures

4 weeks old mice were intravenously injected in the periorbital veinwith AVV vectors containing a Sk-SH4 and CSk-SH5 regulatory element,i.e. AAV9sc-Sk-SH4-Des-Luc and AAV9sc-CSk-SH5-Des-Luc, at a dose of5×10⁹ vg/per mouse.

Heart and muscle tissues harvested from the mice, were submersed inphosphate buffered saline (PBS) containing 1% formaldehyde, cut intosmall pieces and incubated at room temperature for 15 minutes. Fixationwas stopped by the addition of 0.125 M glycine (final concentration).The tissue pieces were then treated with a Tissue-Tearer and finallyspun down and washed twice in PBS. Chromatin was isolated by theaddition of lysis buffer, followed by disruption with a Douncehomogenizer. Lysates were sonicated and the DNA sheared to an averagelength of 300-500 bp. Genomic DNA (Input) was prepared by treatingaliquots of chromatin with RNase, proteinase K and heat forde-crosslinking, followed by ethanol precipitation. Pellets werere-suspended and the resulting DNA was quantified on a NanoDropspectrophotometer. Extrapolation to the original chromatin volumeallowed quantitation of the total chromatin yield. An aliquot ofchromatin (30 μg) was pre-cleared with protein A agarose beads(Invitrogen, catalogue number 15918-014). Genomic DNA regions ofinterest were isolated using 4 μg of antibody against MEF2 (Santa Cruz,sc-313), SRF (Santa Cruz, sc-335) and CEBP (Santa Cruz, sc-150).Complexes were washed, eluted from the beads with SDS buffer, andsubjected to RNase and proteinase K treatment. Crosslinks were reversedby incubation overnight at 65° C., and ChIP DNA was purified byphenol-chloroform extraction and ethanol precipitation. Quantitative PCR(QPCR) reactions were carried out in triplicate on specific genomicregions using SYBR Green Supermix (Bio-Rad). The resulting signals werenormalized for primer efficiency by carrying out QPCR for each primerpair using Input DNA. Primer sequences for Sk-SH4 were:5′-GTCCCTCACTCCCAACTCAG-3′ (SEQ ID NO: 33; forward) and5′-GAGGAGAAGGAGATCAGACACTG-3′ (SEQ ID NO: 34; reverse); for CSk-SH5:5′-TAGCTGGGCCTTTCCTTCTC-3′ (SEQ ID NO: 35; forward) and5′-CGTCTCCCTAGCAGCAACAG-3′ (SEQ ID NO: 36; reverse). Negative controlprimers were purchased from Active Motif (Carlsbad, Calif., USA)(#71012) and are specific for non-transcribed gene sequences onchromosome 17.

Results

The muscle-specific regulatory element Sk-SH4 contains several putativetranscription factor binding sites (TFBS), including E2A, SRF, p53,CEBP, LRF, MyoD and SREBP. Using a chromatin immuno-precipitation (CHIP)assay, binding of CEBP and SRF on the Sk-SH4 element was confirmed inthe heart and skeletal muscle from mice that were injected withAAV9sc-Sk-SH4-Des-Luc vector (FIG. 15 A,B). Similarly, binding of CEBPand MEF2 element on the CSk-SH5 regulatory element was shown in theheart and skeletal muscle from mice injected with AAV9sc-CSk-SH5-Des-Luc(FIG. 15 C,D).

Example 10: Therapeutic Evaluation of Muscle-Specific RegulatoryElements Via AAV Vectors Comprising a Desmin Promoter

The effect of the muscle-specific regulatory element Sk-SH4 on theexpression and therapeutic efficacy of two therapeutic genes, inparticular micro-dystrophin and follistatin, which have therapeuticpotential for the treatment of muscle disease such as Duchenne musculardystrophy (DMD) by gene therapy, was evaluated. MDX-SCID mice replicatethe disease manifestations of Duchenne muscular dystrophy in patientsand are therefore well suited to assess therapeutic efficacy of theAAVss-Sk-SH4-Des-MVM-MD1 and AAVss-Sk-SH4-Des-MVM-FST-2A-Luc vectors.

Experimental Procedures

Cloning Follistatin and MD1 Genes into AAV

The microdystrophin 1 (MD1) (Koo et al., 2011) and follistatin (FST)(Kota et al., 2009) genes were cloned and driven from desmin promoter,which was operably linked to the muscle-specific regulatory elementSk-SH4. The MD1 gene was flanked by MluI and XhoI restriction sites atthe 5′ and 3′ ends, while the FST gene was flanked by MluI and SalIrestriction sites at the 5′ and 3′ ends, respectively and weresynthesized by conventional to oligonucleotide synthesis. The Sk-SH4regulatory element, operably linked to the desmin promoter, was clonedupstream of the MVM intron in the context of a single strandedadeno-associated viral vector (AAVss) backbone. The vector alsocontained a 49 bp synthetic proudfoot polyadenylation site (Levitt N etal, 1989). The follistatin gene was linked to a luciferase reporter genevia a 2A polypeptide. The generated constructs were designated aspAAVss-Sk-SH4-Des-MVM-MD1 and pAAVss-Sk-CRM4-Des-MVM-FST-2A-Luc,respectively, and are schematically shown in FIG. 16.

AAV vector production and purification were carried out as described inExample 2.

Treadmill Test for Phenotypic Correction of MDX-SCID Mice

4 weeks old MDX-SCID mice (bred in house) were injected intravenously ina total volume of 100 μl with a dose of 2×10¹⁰ vg per mouse of theAAVss-Sk-SH4-Des-MVM-MD1 and AAVss-Sk-SH4-Des-MVM-FST-2A-Luc vectors,individually or in combination. 8 weeks post-injection, the treated andcontrol (injected with PBS) MDX-SCID mice were subjected to thetreadmill test. The treadmill tests were performed using the Exer-3/6open treadmill (Columbus instruments, USA). The inclination of the beltwas adjusted to 10° uphill before performing the test. The initial speedwas set at 10 m/min and thereafter the speed was increased by 1 m everyminute. The test was terminated at a point when the mice sat for 5seconds on the pulse grill. At that point the distance covered by themice was recorded and the total distance covered by the mice during thecourse of the test was calculated by using the formula,distance=((N+n)/2)*(N−n+1) where N is the time (in min) at the point oftermination of the test and n is the time (in minutes) at the start ofthe test.

mRNA Analysis

mRNA analysis was performed as described in Example 2. To quantify themRNA of the microdystrophin and follistatin genes, a qPCR-based methodwas used using the primers 5′-GTGCCCTACTACATCAA-3′ (SEQ ID NO:42) asforward primer and 5′-AGGTTGTGCTGGTCCA-3′ (SEQ ID NO:43) as reverseprimer (amplicon 206 bp) for the microdystrophin, and the Luc2-specificforward primer 5′-CCCACCGTCGTATTCGTGAG-3′ (SEQ ID NO: 14) and reverseprimer 5′-TCAGGGCGATGGTTTTGTCCC-3′ (SEQ ID NO: 15) (amplicon 217 bp) forthe follistatin gene.

Results

The results of the treadmill test clearly showed that the mice treatedby gene therapy with either MD1 or FST or the combination of both,outperformed the untreated control MDX-SCID mice (FIG. 17). The MDX-SCIDmice injected with either the AAVss-Sk-SH4-Des-MVM-MD1 or theAAVss-Sk-SH4-Des-MVM-FST-2A-Luc vector covered twice the distancecovered by the control mice. When both vectors were co-injected into theMDX-SCID mice, a distance of 4 km was covered, which is 4 times morethan the distance covered by the control MDX-SCID mice injected withPBS. These results clearly demonstrate that therapeutic efficacy can beachieved using these vectors.

The significant physiologic effect of the gene therapy using theAAVss-Sk-SH4-Des-MVM-MD1 or the AAVss-Sk-SH4-Des-MVM-FST-2A-Luc vectoror their combined use was confirmed by histologic examination.Hematoxylin/eosin-stained muscle sections were scored for % centrallynucleated cells for the different experimental groups (FIG. 18). Themuscle sections of C57B6 wild-type mice showed predominantly peripherallocalization of the nucleus in the myofibers (data not shown) and aminimal percentage (<2%) of the nuclei was centrally located (FIG. 18B).In untreated, control, MDX/SCID mice, the nuclei were predominantly(about 50% of the nuclei) centrally located in the transversallytransected myofibers (FIG. 18Aa, FIG. 18B). MDX/SCID mice injected withAAVss-Sk-SH4-Des-MVM-MD1 (AAV9-MD1) (FIG. 18Ac, FIG. 18B) orAAVss-Sk-SH4-Des-MVM-FST-2A-Luc (AAV9-FST) (FIG. 18Ab, FIG. 18B), allshowed a decreased number of myofibers that are centrally nucleated.Co-administration of both, AAVss-Sk-SH4-Des-MVM-MD1 andAAVss-Sk-SH4-Des-MVM-FST-2A-Luc vectors, resulted in an even moreprofound shift in nuclear localization towards the periphery of themyofibers, and a further reduction in the percentage of centrallylocated nuclei (FIG. 18Ad, FIG. 18B). These results are indicative of areduced regenerative stimulus and phenotypic correction after the genetherapy. Consequently, the shift of nuclear localization from a centralto a more peripheral location in the myofibers is consistent with thephenotypic correction as shown by the improved muscle strength andmobility in the treadmill assay.

Using quantitative RT-PCR, the expression of the micro-dystrophin (MD1)and the follistatin (FST) genes in biopsies from heart and muscletissues, in particular gastrocnemius and quadriceps, of the miceinjected with the pAAVss-Sk-SH4-Des-MVM-MD1 construct, thepAAVss-Sk-SH4-Des-MVM-FST-2A-Luc construct or the combination of bothconstructs was assessed (FIG. 19).

Example 11: In Vivo Comparison of Muscle-Specific Regulatory Elementswith CMV and SPc5-12 Promoters Experimental Procedures

AAV vector production and purification were carried out as described inExample 2.

The AAVsc-Des-MVM-Luc vector is a self-complementary AAV vectorcontaining a luciferase (Luc) transgene driven from the desmin promoter.The scAAV vector backbone also contained a Minute Virus of Mouse (MVM)intron and a Simian Virus 40 (SV40) polyadenylation site (pA).

The AAVsc-SPc5-12-MVM-Luc vector had the same configuration as theAAVsc-Des-MVM-Luc vector, but the desmin promoter was replaced by theSPc5-12 promoter.

AAV vectors comprising the muscle-specific regulatory element Sk-SH4were generated according to the protocol described in Example 2.Briefly, the muscle-specific regulatory element Sk-SH4 was synthesizedby conventional oligonucleotide synthesis and cloned upstream of thedesmin or the SPc5-12 promoter in the context of the AAV vector backboneof AAVsc-Des-MVM-Luc or AAVsc-SPc5-12-MVM-Luc, respectively.

The AAVsc-CMV-Luc vector was generated by cloning the Cytomegalovirus(CMV) promoter (SEQ ID NO: 30) upstream the luciferase reporter geneinstead of the desmin promoter in the context of the AAV vector backboneof AAVsc-Des-Luc, which also contained a polyadenylation site (pA).

A schematic representation of the different vectors is shown in FIG. 20.

Adult CB17/IcrTac/Prkdcscid mice were intravenously injected with thedifferent vectors (n=3) at a dose of 1×10¹⁰ vg/mouse.

mRNA analysis was performed as described in Example 3.

Results

Luciferase mRNA levels in mice injected with a vector that expressed theluciferase gene from the desmin promoter operably linked to themuscle-specific regulatory element Sk-SH4 were compared versus mice thatwere injected with a vector that expressed the luciferase gene from theCytomegalovirus (CMV) or the SPc5-12 promoters, which were not operablylinked to a muscle-specific regulatory element. The CMV and SPc5-12promoters are considered the most powerful promoters known to allowrobust gene expression in the heart and skeletal muscles. FIG. 21 showsthat the vector comprising the Sk-SH4 muscle-specific regulatory elementof the invention operably linked to the desmin promoter allows for muchbetter expression than the vectors comprising the CMV or the SPc 5-12promoter without muscle-specific regulatory element.

Similarly, when the Sk-SH4 muscle-specific regulatory element wasoperably linked to the SPc5-12 promoter, increased luciferase mRNAlevels were observed in the heart and all skeletal muscle types tested(FIG. 21). However, the mRNA level induced from this construct was lowerthan when the Sk-SH4 muscle-specific regulatory element of the toinvention is operably linked to the desmin promoter.

1-18. (canceled)
 19. A nucleic acid expression cassette comprising atleast one nucleic acid regulatory element for enhancing muscle-specificgene expression, operably linked to a promoter and a heterologoustransgene, wherein (i) said nucleic acid regulatory element comprisesthe sequence set forth in SEQ ID NO:1, a sequence having at least 95%identity to the sequence set forth in SEQ ID NO:1, or a functionalfragment thereof, wherein said functional fragment comprises at least 20contiguous nucleotides from the sequence from which it is derived, andwherein said functional fragment comprises at least 1 of thetranscription factor binding sites (TFBS) that are present in thesequence from which it is derived; or (ii) said nucleic acid regulatoryelement hybridizes under stringent conditions to the sequence set forthin SEQ ID NO:1, a sequence having at least 95% identity to the sequenceset forth in SEQ ID NO:1, or a functional fragment thereof comprising atleast 20 contiguous nucleotides from the sequence from which it isderived and comprising at least 1 of the transcription factor bindingsites (TFBS) that are present in the sequence from which it is derived,or to a complement of any of said sequences.
 20. The nucleic acidexpression cassette according to claim 19, wherein said nucleic acidregulatory element enhances cardiac and skeletal muscle-specific geneexpression.
 21. The nucleic acid expression cassette according to claim19, wherein said functional fragment is a nucleotide sequence selectedfrom any one of the following: positions 33 to 58 of SEQ ID NO:1,positions 90 to 142 of SEQ ID NO:1, positions 143 to 233 of SEQ ID NO:1,positions 240 to 310 of SEQ ID NO:1, and positions 90 to 233 of SEQ IDNO:1.
 22. The nucleic acid expression cassette according to claim 19,wherein said nucleic acid regulatory element has a maximal length of 600nucleotides.
 23. The nucleic acid expression cassette according to claim19, wherein the promoter is a muscle-specific promoter.
 24. The nucleicacid expression cassette according to claim 23, wherein themuscle-specific promoter is selected from the group consisting of: thedesmin (DES) promoter, the myosin light-chain (MLC) promoter, theSPc5-12 promoter and the muscle creatine kinase (MCK) promoter.
 25. Thenucleic acid expression cassette according to claim 19, wherein thetransgene encodes a therapeutic protein, an immunogenic protein, or astructural protein.
 26. The nucleic acid expression cassette accordingto claim 19, wherein the transgene encodes a secretable therapeuticprotein or a structural therapeutic protein.
 27. The nucleic acidexpression cassette according to claim 19, wherein the transgene encodesa plasma factor.
 28. The nucleic acid expression cassette according toclaim 19, wherein the transgene encodes dystrophin or a sarcoglycan. 29.The nucleic acid expression cassette according to claim 19, wherein thetransgene comprises the microdystrophin 1 (MD1) gene or the follistatin(FST) gene.
 30. A vector comprising at least one nucleic acid regulatoryelement for enhancing muscle-specific gene expression, wherein saidnucleic acid regulatory element: (i) comprises a sequence set forth inSEQ ID NO:1, a sequence having at least 95% identity to the sequence setforth in SEQ ID NO:1, or a functional fragment thereof, wherein saidfunctional fragment comprises at least 20 contiguous nucleotides fromthe sequence from which it is derived, and wherein said functionalfragment comprises at least 1 of the transcription factor binding sites(TFBS) that are present in the sequence from which it is derived, or anucleic acid expression cassette comprising the at least one nucleicacid regulatory element, operably linked to a promoter and a transgene;or (ii) hybridizes under stringent conditions to a sequence set forth inSEQ ID NO:1, a sequence having at least 95% identity to the sequence setforth in SEQ ID NO:1, or a functional fragment thereof comprising atleast 20 contiguous nucleotides from the sequence from which it isderived and comprising at least 1 of the transcription factor bindingsites (TFBS) that are present in the sequence from which it is derived,or to a complement of any of said sequences, or a nucleic acidexpression cassette comprising the at least one nucleic acid regulatoryelement, operably linked to a promoter and a transgene.
 31. The vectoraccording to claim 30, which is a viral vector.
 32. The vector accordingto claim 31, wherein the viral vector is an adeno-associated viralvector.
 33. A pharmaceutical composition comprising the nucleic acidexpression cassette according to claim 19, or a vector comprising thenucleic acid expression cassette, and a pharmaceutically acceptablecarrier.
 34. A method for gene therapy comprising administering to asubject in need thereof an effective amount of: i) the nucleic acidexpression cassette according to claim 19; ii) a vector comprising thenucleic acid expression cassette; or iii) a pharmaceutical compositioncomprising the nucleic acid expression cassette or the vector and apharmaceutically acceptable carrier.
 35. The method according to claim34, wherein said gene therapy is for the treatment of Duchenne musculardystrophy (DMD), a congenital myopathy, limb girdle muscular dystrophy,a metabolic myopathy, a cardiomyopathy, cardiac hypertrophy, hearfailure, a distal myopathy or a cardiovascular disease.
 36. The methodaccording to claim 34, wherein said gene therapy is for the treatment ofDuchenne muscular dystrophy (DMD) and wherein the transgene encodes amicrodystrophin or follistatin, or wherein said gene therapy is for thetreatment of limb girdle muscular dystrophy and wherein the transgeneencodes a sarcoglycan.
 37. A method of vaccination comprisingadministering to a subject an effective amount of i) the nucleic acidexpression cassette according to claim 19; ii) a vector comprising thenucleic acid expression cassette; or iii) a pharmaceutical compositioncomprising the nucleic acid expression cassette or the vector and apharmaceutically acceptable carrier.
 38. An in vitro or ex vivo methodfor expressing a transgene product in a muscle cell comprising: i)introducing a nucleic acid expression cassette according to claim 19, ora vector comprising the nucleic acid expression cassette, in a musclecell; and ii) expressing the transgene product in the muscle cell.